What benefits??? the nuclear bomb bomb analogy is terrifying so... wipe out competition, force us stay on their platform for games who once were available everywhere. yeah sounds like a wonderful future for gaming.
I mean, yes, totally with you (and I'm a PlayStation gamer primarily, so right now I have a little bit of that feeling of, "Uh, what, our Emperor is no longer a god??"), but...
The one thing about the nuclear analogy that I am reckoning with is that I don't think this nuke is aimed at Sony, per se. It's aimed at the Netflixes and Disney Pluses. Already, Xbox is competing for eyeballs/attention with everything else kids can do these days, and Microsoft won't be in the business of selling Xboxes forever. As with most entertainment mediums, "services " will be the future of getting games. Streaming will probably take over* (as much as die-hards hate it and will fight against it or to subvert it,) at some point in the future when the price point and performance threshold convinces gamers to choose convenience over direct physicality. It's why Amazon and Google have been trying to get into gaming (albeit with lots of difficulties), because their devices aren't seen as Amazon Prime Video or Google Play devices; they're the portals to everything you do for fun.
(*I want to be careful about saying "streaming is the future, I know it's a battleground concept for hardcore gamers. But if not streaming, some other "service" will be how you get what you want instead buying a disc or paying for a download. Already, the Game Pass deal is seen as too good to pass up, and users are wondering why they ever need to buy a full game again when they're building their backlog every month just buy subscribing. And it's just getting started...)
What happens when you can get Xbox Game Pass not just on your Xbox game console or a PC, but on the tablet or smartTV you already do everything else on (including another Xbox, but maybe also a Switch or a Oculus Quest or whatever is the future of gaming?)
What happens when the whole Xbox business is compressed down to an App you install on all your devices?
As that transition happens, media will coalesce under specific ownership, because it makes it hard to be an independent publisher when A) the service is also in the production business and makes more money if it creates its own titles O&O, and B) putting the same product on every different service makes paying into more than one service seem a questionable subscription even if it's the exclusives that brought users in at first. We will see what happens to the EAs and Ubisofts and THQ Nordics of the world (most have initially tried to start their own services with their brands, just like CBS/Paramount and Universal and Viacoms have, but you need both the names and the backing to go that big and even major studios are confused what's ahead when there doesn't seem to be any deals for anybody but those who podium.)
The Xbox service aims to finish the battle before it even starts, and to do so, it will need weapons. Microsoft is aiming to become the Netflix of the gaming future, not the Paramount+ or Peacock. Halo and Forza are enough to sell a console, but once you're competing with everything all at once, a subscription service needs a more steady supply or people will find another option. And although the Xbox ecosystem already had Elder Scrolls and Doom and Fallout and everything that this buyout absorbs, being able to say that these are Xbox Game Pass titles instead of just games that are also on Xbox as well as elsewhere is a statement that demands users get Game Pass. They can afford to let Sony or maybe Nintendo have a sip still if they choose to let some franchises continue to also appear elsewhere (it might even be good brand awareness since MS doesn't need to actually drop the nuclear bomb in order to establish itself as a superpower, they just need to be the one with their finger on the button,) because that conversion may be a little bit down the road (and may/probably will happen different than it has happened in other entertainment forms.) But when the time comes, they want to make sure that the competition can not compete.