I am saying it would be a small niche if the major reason for PC games to be popular was graphics.
Still sounds like two separate arguments, but we can go ahead and talk about this now if you want... Define "small"? It's big enough for AMD and nVidia to release expensive graphics cards every year and even hold media events to talk about them. It's big enough for MS to get off it's ass and develop DX12 and it's big enough that games that cost millions to make are being released for PC with PC specific features added in.
I just don't see the point you're making.