It's not about how many Microsoft owns. It's how large the ones they own are. Microsoft has essentially made long time huge third party developers/publishers part of their company now, that's corporate consolidation and should never be defended or justified in any way.
Microsoft has trillions of dollars. They have the capital, workforce, and time to build up their own studios. If the only way a trillion dollar company can "compete" in a space is to consolidate that space by applying anti consumer tactics like buying out longstanding publishers, that's stupid and a lie.