Big Corps aren't the issue (or well they are but not because they're big corps), they only become an issue when a regular tool in their playbook is Embrace, Extend, Extinguish. See Facebook, XMPP and the effect that hostile takeover had on their recent plans to create a Fediverse platform. I agree that the Microsoft hate is overblown and unhealthy but to pretend that Microsoft engaging more in Linux is something to be enjoyed without worry is equally a bad idea. There is no guarantee they'll try to shoehorn their own bad ideas into Linux and quite frankly I think Linux is too big for them to manage that but it is a concern nonetheless.

Still at least with Linux there are plenty of other giants who have a vested interest in making sure the status quo is upheld with no single company having a monopolistic influence on the development so I don't think there's any reason to worry about the Embrace, Extend, Extinguish playbook working here at all.