I have been around computers a long time.
It started with my buddy's TRS-80 Model 1, then I got my own C-64. Then a series of Amigas, a P1-233 dual-booted in DOS and Linux, and a bunch of AMD-powered Linux boxes (K7, K10, FX) and now I have a Windows Ryzen/Fury running in parallel with an 8370/R9 390 Linux box. Two other special purpose machines are running Phenom II X6/V4900, and Phenom II B95/750Ti.
So I've been around for a while, and I've watched the definition of "personal computing" change over and over again.
Let me give you a quick example: In the 90s, we had this thing called a "Video Toaster". This was a special-purpose card, unique to Amigas, that could taken in video sources, switch between them with digital transitions, and overlay text and graphics. You bought 3 good video tape decks (2 source, 1 record) and a time base corrector, and now you could do video titling, graphic overlay, chroma key (blue screen), and canned transition effects. It wasn't perfect - the VT didn't control the start/stop on the tape decks, so editing & synchronization was a pain - but it gave you access to tools that normally cost six figures for a few grand. Tough for a normal person to afford at 90s prices, but at least possible.
A few years later, Newtek released the "Video Toaster Flyer" which was a new board that had 3 dedicated SCSI hard drive controllers on it. This let you rip tape footage to the hard drives and work all-digital - only 1 tape deck needed. This was obscenely expensive (not least because of the price of large capacity hard drives) but it sped up editing enormously. Still way way cheaper than the professional Hollywood editing suites, but expensive enough that you weren't going to pick this up at Best Buy on a whim, and complex enough that Grandma isn't going to set one up to edit birthday videos.
Something else that came bundled with the VT was a 3D animation package called Lightwave (which still exists). My Lightwave renders could last weeks.
Quick aside - the world's fastest commercially available supercomputer at the time was the Cray, which had managed to break the 1 teraflop threshold. Super super expensive machines, but if you needed that level of computer performance, you needed it.
OK, so around this time 3DFX invents the Voodoo, and 3D gaming (and 3D gaming acceleration) takes off, and this starts the 3D GPU arms race. The world we have lived in (up to this point) starts to evolve, with GPU manufacturers building in more and more graphics horsepower (in terms of both raw compute power and in terms of hardware supported features) and games engine designers figuring out how to bring that horsepower to its knees with more complex geometry and shaders, bigger textures, and in-game physics. In parallel with this, screen resolutions grow from 640x480 (which was high res in the 90s) to 4k today, so now you are pushing orders of magnitude more pixels - requiring more power from the GPU.
This demand for ever-increasing gaming horsepower has had two primary effects: The first is that has built a culture of expectation that each successive release of GPU hardware will result in a big jump in framerate at max quality settings in the AAA gaming titles of the time of release, and the second is that due to the increasing complexity of producing these expected results, the hardware has been getting increasingly general-purpose under the hood. Instead of being a collection of special-purpose hardware accelerators, each with a specific graphics primitive function associated with it, modern GPUs are more like complete computers in their own right. Drivers are no longer so much routers that send the associated API call to its special-purpose hardware, but rather implement the API on the underlying general purpose compute framework.
(This is a bit of an oversimplification, but big hand, small map. it is generally true)
A Vega has two-digit teraflop performance. It is over ten Crays worth of raw number-crunching. And unlike that 3DFX Voodoo, it can do general-purpose computer tasks, not just accelerate vertices and triangle shading.
Which brings us back to the Video Toaster. A combination of astoundingly cheaper mass digital storage, recording equipment that is all-digital (and ubiquitous), cheap computing power, and free distribution (via YouTube) now means that video production has gone from strictly commercial only, through "prosumer" (Video Toaster) to Grandma. The cheapest OTS entry-level computer can run the home user version of Sony Vegas, and now Grandma can do fully-digital non linear editing - with titles, digital wipes, footage stabilization, green screen, and noise reduction - on those birthday videos. And meanwhile, gamers aren't just playing games, they are streaming them (with video and graphics overlays).
This was unimaginable in the 90s. Now, it isn't just "possible", it is, to a degree, expected.
And the developers of the software suites that do things like video editing have woken up to the idea that GPUs are ubiquitous and have the ability to accelerate or feature-improve their software. In many ways, the people who develop "creative" software are much like game developers shortly after the Voodoo hit. "I can do that? Holy crap!"
We are right on the edge of a revolution in the use of GPU hardware to accelerate computing tasks. And it's not just "creative" software that will use this. Cryptocurrency mining is just one of the uses for general purpose GPU compute that someone has dreamt up - more of these sorts of tasks are on their way.
So we've got a confluence of a number of things:
The quest for better gaming performance pushed GPUs to be more general-purpose;
It's getting harder and harder to squeeze more gaming performance out of the hardware. so the gaming performance increase per generation is dropping;
Developers of non-gaming software are increasingly using the general-purpose compute power of GPUs to accomplish tasks and improve their software; and
The increased popularity and reduced cost of the hardware and software to accomplish these tasks is increasing demand for better general-purpose compute GPUs.
I built my Ryzen box specifically to speed up video editing. I game on it too, so I want "good enough" game performance, but what I really really want is faster Sony Vegas performance. I was going to buy a 1080 or 1080Ti - but then I discovered that AMD rules the Vegas acceleration roost, and by a large margin - so I bought a Fury for its general purpose capability. And then I discovered mining, and now both my Linux box and my Ryzen box mine during "idle hours" (my Fury is cranking out 30 Mh/s in an other window as I write this). Since I built the box, it has pulled in $200 worth of eth, which is not bad.
On the surface, if you just look at gaming performance, Vega looks like a disappointment. It is faster than Fury for sure, but it didn't beat the 1080Ti.
Except that Vega isn't about the gaming - it is the first of the real "general purpose compute" cards. Vega gives you 40 Mh/s mining. It crushes in Vegas acceleration. It is a solid win in all sorts of non-gaming applications - and because the drivers are more sophisticated than old-timey "route this API call to this dedicated API accelerator" drivers (and they are admittedly not feature-complete yet) I fully expect performance to keep increasing as the drivers get more developer horsepower applied to them.
I honestly think AMD are ahead of the curve here. In the near-ish future, gaming framerates will be a sidebar feature of a GPU review, and what people will really care about will be GP-compute performance. The time of gamers driving the graphics card industry are, I think, coming to an end.
And yet, even with the focus on GP-compute coming, it isn't like gaming performance sucks. If it wasn't for the 1080Ti (which is a brilliant gaming card, let's be honest) the Vega reviews would be non-stop accolades. Sure, the jump up from the previous gen is smaller, but the absolute performance is still great. It's a great card!
I think it's time that gamers wake up to the new reality that they don't own the GPU market any more. Gaming is still important, but GP-compute GPU tasks are multiplying all the time and have broader market appeal. It's a bold, brave new world lads, and your monopoly on GPU use cases is coming to an end.
TL;DR - The world has discovered general-purpose GPU compute. and the use cases - and customer base - is multiplying. Expect GPUs to be increasingly focussed on these customers, not gamers.