Well, there are a lot of web developers that we're saddled with supporting ie6 for many years after Microsoft won the browser war with Netscape and proceeded to let it stagnate for years. That amount of pain that was inflicted on the web dev community left a lot of lingering resentment.

Then there was their locked-down file formats, their role in killing off BeOS and preventing pre-installed Linux machines, their "embracing" of open technologies like Kerberos only to make their version subtly incompatible. For well over a decade, almost everything they did technically rubbed us tech folks the wrong way.