I think your argument works if people were saying that PC gaming is better because PC games are better. But that's not what anyone is saying, so your point sort of falls flat. People are saying PCs are better because they provide a better environment to game in. Their supporting points include but are not limited to:
- free online - Huge Benefit across the board
- near infinite backwards compatibility - Also Great
- robust settings options - Enthusiast specific. Most people dont want to tinker
- high scaling with better hardware - Investment specific. Ignores challenges associated with doing hardware yourself
- VR support (which should scale much better than Morpheus, of course) - Cant comment on this one
- mod support - Huge but enthusiast specific and the range of accessablity varies wildly... Like when my friend was trying to mod Fallout 3
- support for any and every type of USB controller and peripheral input (including all of your favorite X360, XOne, PS2, PS3 and PS4 compatible controllers) - Awesome perk but not exclusive to PCs
- modular nature allowing for part upgrades as you see fit - Consumers dont like to shouldler the liability and maintenance. This is an DIY enthusiast benefit
- emulation - Awesome but not PC specific
- open nature - Comes with all the pros and cons open platforms provide. Not the only open platform option available
- lower prices - Definitely in PCs favor but Consoles are catching up and so are retailers
- higher income for developers - This one is dubious. This has to vary wildly. I suppose across the board the early access model is far more prevalent and profitable for creators. This hasnt stopped creators from being EVERYWHERE. I think its more important for creators to cater to the best possible audience. Sometimes that PC sometimes it isnt... Though i bet the overall average trend favors PC
- comfy couch TV play with big picture mode and any of a variety of control options, making PC more TV friendly than ever before - OK... Big picture is great. But one doesnt just buy a PC off the shelf and hit the ground running. This is why the whole idea of Steam Machines and Steam OS even exist.
It's an argument that is less about games (which turn into a subjective debate and purely a matter of taste, as we all understand) and more of an objective debate about features and the nature of the platforms themselves.
With the number of features that have been downgraded going from last gen to this gen on consoles, rising prices for online play, royalties, and expensive peripherals that have to be re-bought again and again (I refuse to upgrade my TE arcade stick. Fuck you), it seems like a sound argument to me. Before even discussing 720p/900p and 30fps disappointments that highlight this generation.