True, but that's just more of an added benefit of PC. I have to assume the vast majority of people who build PCs for games have the desire to play new games that come out. There may be a few people who build PCs with only the desire to play old games. But i don't think that is the majority.
Plus if someone doesn't want new games then they wouldn't need or care to upgrade their console from one gen to a next. So i don't think that's relevant in this discussion.
I'll try to respond below. Lemme know what you think:
Consoles:
Need to upgrade every 5-7 years if you want to play new games on next gen consoles. Can play your old games indefinitely.
PC:
Need to upgrade every 5-7 years if you want to play new games that are more demanding and require next gen parts. Can play your old games indefinitely.
In terms of playing new games on an old PC, try playing cyberpunk on a PC from 2013 (7 years prior to CP77 release in 2020). You'll get like 2 fps. Not even playable.
So to conclude, sure, you can try to play new games on your old ass PC, but it'll run like crap and won't be a good experience.
Edit: just to clarify, my opinion is from the perspective of someone who wants to play new demanding games. If you play super easy to run new indie games, then yea I agree with your point. Added benefit of PC is the ability do that indefinitely.