I feel like Sony has been making these kinds of purchases (studios already working with them almost/entirely exclusively) as more of a prevention of Microsoft buying them up. It's a weird opposite: When Microsoft purchases a studio, it feels like it is expanding with additional exclusive content, whereas when Sony purchases a studio nothing really changes as these studios already were focused on making Sony exclusives. I'm not criticizing anything, just pointing out that Sony is more on the defense from my perspective. Why else would Sony buy up a studio that was already making exclusives for them if not to prevent someone from buying them up that would prevent their games from being on PlayStation? Microsoft is really the only major threat there. I doubt Sony would care if a third party company had bought out Insomniac, Firesprite, or any other studio they've obtained in recent years because then they could still arrange for those studios to make exclusive games for them. The only one that is threatening the status quo is Microsoft, so Sony seems to be on the defense by locking down these pseudo-independent studios and making them first party studios. Obviously my view is based on more of a general view of their purchases and not all-encompassing.
For context about this studio, here are games they made:
Game we know they are working on:
Theaters of War game mode for Star Citizen (a game that will no doubt release for the PS10, XboxOneTwoThree, and SViwtch.
Nah, this isn't it. The now defunct Liverpool team (previously Psygnosis) was closed down and a lot of the members of that moved and created this FireSprite.
Sony acquires studios that they know well and worked with and with 250 people in this one this is a pretty big buy. Also adding to that they're pushing VR with PSVR 2 (soon) so they're going to need a big studio or two pumping out games for it.
So you don't think Sony being concerned about MS buying this studio up, whom they have worked with over the years on PS exclusives, is a factor? If anything their importance to PSVR that you mentioned highlights more of a reason on Sony's part to prevent these types of studios from being bought out by MS. And sure, they've not made xbox games before, but if MS likes the quality of their games and they are willing to spend billions of $ on obtaining studios, why wouldn't they want to add a quality candidate that happens to have a history of working with, primarily, Sony?