For people who lived through the 80's, we saw how Microsoft killed huge companies that dominated their product category, like Lotus, WordPerfect, and Netscape, leading to an antitrust judgement against them for bundling products with Windows to take over markets. I think it feels different to us than it does to a younger generation that has not experienced these tactics first-hand.
But, I don't think Microsoft is unique at all. I think all huge companies try to dominate their category, and have no problem in being ruthless to do that. Amazon acquiring diapers.com for example:
http://allthingsd.com/20131010/how-jeff-bezos-crushed-diaper...
Google does it by making people jump through hoops to enable IMAP access to gmail accounts, making it harder to transition to a different email provider.
Google and Apple do it with their app stores, allowing them to be gatekeepers for who succeeds and who doesn't. If an app gets popular, they have all the metrics to know when to launch a competing app, and can delist the original app, saying "it doesn't add value to the standard phone package". Or whatever other crap they want to do.
Microsoft is a huge corporation. Like other huge corporations, they only make moves that they believe will increase their profits, and they have enough cash and revenue to play an extremely long game, as in, a decade.
Just for example, let's say Microsoft Linux becomes the largest Linux distribution in the world. That gives Microsoft a lot of power and control over the Linux ecosystem.
With their ownership of GitHub, they have a "pulse" like no one else on the software development side, similar to the way Amazon has a pulse on all 3rd-party sellers on it's own site, and uses that to enter product categories, underpricing competitors, etc. What will Microsoft do with that knowledge? We don't know, but they aren't giving everyone else equal access to it, just like Amazon isn't publishing a big list of the most successful products, so apparently it is valuable, or they'd share it.
That's an easy way to look at things Microsoft and other big corporations do: do they allow everyone to have the same access they have, or do they keep an advantage for themselves that others don't have? In most cases, it is the latter.
Another common analogy: boiling a frog. You don't throw the frog in a boiling pot of water; you put it in a pot of cold water and gradually heat it. The frog is perfectly content until it is dies. Microsoft is not going to make a big announcement like "We intend to be the largest Linux distribution in the world within the next 10 years", even if that is their goal, because that would probably freak people out and they would not go along with their agenda. They have to get people to follow the piper to their goal. I'd love to see their 10-year plan for Linux domination.