When you're ubiquitous...
...you get kicked
I know we're all professionals here, but I find it almost impossible to imagine what the world would have been like *without* Microsoft (free downvote for first person to say "better"). Sure some stuff was bad (my personal nadir is Win8), but some stuff was incredible. Visual Studio was pretty revolutionary, to name just one.
But over and above individual 'good' or 'bad' products, they went a long way to inventing the modern software industry. They realised that having a strong application ecology would be mutually beneficial to them and countless small (some becoming huge) software producers. And they never thought to take a slice of that income (I'm looking at you Apple - still seems unbelievable to me that Apple take 30% of every iPhone app sale)
Full disclosure: I worked for Microsoft for a couple of years. They were exactly how you'd imagine a huge international company - some amazing and brilliant bits, some terrible and mad bits)