They're not thinking about these things as games, generally, but specifically how they'll be perceived by the Xbox audience. It looks to me like they discounted BG3, at least in part, because it couldn't split-screen on series S. They're thinking about games you play on the couch, in a group, maybe during a party - not games you play solo for hours or days on end.

That may end up being a self-fulfilling prophecy. BG3 isn't out on Xbox (officially) yet. We don't know what their advertising will look like, and it well turn out that everyone who wants to play it will already have gone the PC route.