I don't think it's fair to include Microsoft in that list. They buy game studios so they can close them and shelve their IP after several attempts to turn beloved franchises into GAAS products. They're less of a game studio conglomerator and more of a recycling bin.
Depends on which era of Microsoft Game Studios / Xbox Game Studios you are talking about. Also, Microsoft has never really shelved IP ever, even Flight Simulator is back out of retirement! They've sold IP back to (nearly) the original developers, which is somewhat unheard of outside of Microsoft (Fasa's BattleTech/Mech Warrior and Shadowrun IP brands are back in the "indy space" because Microsoft sold it back; you rarely hear of an Activision or EA IP getting sold back to small developers). Even Microsoft's worst turnover period of developer subsidiaries had some interesting mitigating circumstances: Bungie wanted to be independent again (and again that's a weird case where you'd be surprise to see a developer like Bungie spin back out of an Activision or an EA; Bungie themselves had to do a ton of work on their publishing contracts to avoid being swallowed up by Activision with Destiny), and rumors are that whatever happened to Lionhead may have been a suicide, though who knows if the story will ever be substantiated one way or the other (and Lionhead's IP hasn't been "shelved" for long either with Playground Games working on a new Fable).
