Hardly matters to console gamers.
This thing needs to compete with the console market to be relevant, and having an infinite amount of random Steam games won't matter much, because it's not like we are not getting all the games we want on PS5 and Series. I can't name a single game available on Steam, that I want to play, and that is not Series.
And there are also games available on Series that are not on Steam, on top of it...