I think the argument that Xbox games (and to a lesser degree PS games) can also be played on PC and thus will affect the console sales negatively is overstated. Many (most?) including myself simply don't like to play in front of a computer, it's simply not as comfortable as on the couch. Yeah, I know that you simply can link your PC to a TV or share your screen from the PC to your TV. But honestly how many do that? Very very few. The great majority simply doesn't want a PC tower in the living room and have only one (if at all) beefy PC and if it would stand in the living room it is inconvenient to use it for working/school purposes. And how many people even know about screen sharing? I don't know, maybe there would even be a latency problem if the PC and TV stand in different floors. But anyway, it is again too inconvenient for the great majority of people to start the computer and screen sharing in the upper floor and then go down to your TV at the lower floor (or even just different rooms if both are on the same floor).
The bottom line is, even in the past when 3rd party games looked miles better on a potent PC than on a console, many (most?) people simply didn't bother about gaming on a PC. Console gaming meant and still means convenient plug-in and play. Even though, nowadays, a PC is basically also just a plug-in and play machine for gaming, it is not and probably will never be perceived as such. On the other hand, I can perfectly understand why certain people prefer gaming on PC and probably never bother about buying a console. It's simply a different experience and it's good like that - diversity was always and always will be good for the industry!