Exactly. It's stupid to believe that it'd be practical to spend that much money, then strip half your consumer base from being able to buy the games, effectively cutting into your future profits with the companies you just bought out.
It makes more sense to just run things the way they currently are, by selling to as many as possible. Them upside to MS owning these now, is that Sony cannot outright bribe Bethesda for future titles to go exclusive to PS5, because MS owns them directly. Either that or MS takes the silly bribe and pockets more cash, but if I were them, I'd deny the bribe and just keep going forward with business operations.
There's a reason why MS kept making sure Minecraft reached as many platforms as possible. They'll do the same with these studios as well. They don't care about one box of plastic, because they are more focused on creating a single giant ecosystem.
Minecraft was a pretty different situation. It's a kids property and MS was likely keen not to limit its ability to reach kids so they could merchandise toys, clothing, and other products. Kids don't have the disposable income to buy multiple systems quite often.
Similar thing with Cuphead, they're allowing it on different systems.
Halo, Forza, Gears though ... nothing, nada on Playstation or Switch. I think Bethesda's IP will fall into this category. You want to play those games and you have to buy a XBox, Windows PC, or Game Pass.
Who knows too, there may well come a day when MS pulls Minecraft from other platforms. It's their IP, they're under no obligation to share it.