That's what a "Console Exclusive" is.
Again, the number of gamers who own both a gaming-class PC and a console are a tiny niche. Every game that isn't on the PS5 is an effective exclusive to the Xbox for the overwhelming majority of prospective console buyers. The PS5 doesn't get to claim the PC library as its own. The cheapest method to get these games on the other side of that wall, ironically, would be for a PS5 owner to buy an XSX.
Game Pass is hands down the best service in gaming. You could have just bought that game (for 20% off via the Xbox store price if you liked) and continued playing your save state. Then unsubscribed if that was the only game you cared about. PS Now any every other service that maintains a rotating library will sometimes do this.
Game Pass is a first party service. How does Netflix make money for movie studios when people aren't buying Blu-Rays?
Subscriptions, subscriptions, subscriptions.