Microsoft is the heart of corporate America, it's a facepalm to imagine that any dollar they spend isn't in their own long term interest to make money. It would be illegal for them not to. You can apply that to any large corporation but the problem is by definition how Microsoft makes money.
How does Microsoft make money? They make money by renting from a platform which is monopolistic and enforced. What do they do to maintain this? They deliberately force people onto their platform by abusing their market position, and try to crush any opposition by any possible tactic, including dubious legal cases designed just to bankrupt their opposition. What else do they do? EEE, and also just blatant unnecessary reinvention /ripping off and lock-in when they get the chance.
They didn't abandon some of the visible tactics and start paying open source because they had a moral revelation, it's a company with the same business model it's not possible. Those tactics were just inneffective and co-opting, more subtle EEE has to be the game plan.
Why does that make me angrier than equally evil Facebook/Apple? Well if I was a farmer driving around one of those trucks with source code preventing me from fixing it I'd be pretty personally furious. But I'm not, I'm a developer and those guys are the ones trying to make everyone drive the coding equivalent. But it's worse, because coding isn't just my livelihood, it's a lot of how I think and express my thoughts. They're not messing with my job they're trying to restrict the way I think, so their shareholders can make a buck.
"Microsoft is running Github for charity" have a word with yourself.