Microsoft was the bad guy in a movie where you have a war right before aliens invade and you figure out that there's bigger enemies.
FSF hated Microsoft because they released binaries without source code, they were THE enemy, nowadays, you are lucky if you get a binary to study and modify! The standard from any competitive developer is to hide the binary and source behind a server. Try to study and modify that!
> FSF hated Microsoft because they released binaries without source code
I think that's a bit of an oversimplification - FOSS-leaning people had a pretty large set of reasons to dislike and distrust MS back then. "Embrace, Extend, Extinguish" was a big one, calling linux/FOSS a cancer, their money and influence being used to fund the whole SCO debacle amongst other things. They were pretty actively evil, not just "closed source".
There was very good reason not to let MS gain de-facto control of an open protocol, because 90s and 00s microsoft would not have hesitated to find ways to use that dominance to screw the competition.
For the FSF, Microsoft releasing binaries without source was reason enough to hat them but it was not the only reason why people, including those in the FSF, hated them. Microsoft was very much a company that used their dominant market position to lock customers in and the competition out. (Remember embraced, extend, extinguish?) The Microsoft of today looks like a cuddly teddy bear in comparision.