They were infamous for getting small companies in under NDA, then grabbing their tech, and dumping the small companies (often putting them out of business). They are not alone in this (Apple has done the same thing. I think they even have a term for it -"to Watson" * ). It's just that MS was the most egregious.
It makes me sad to see they are still doing it. I've been fairly impressed by what Nadella has done.
* EDIT: As adamdavidson pointed out, the term that everyone uses is "Sherlocked."