I recently left Microsoft for a startup, but spent about 4 years there on several teams. From my experience nobody really hates anyone. The tech industry is still a fairly small community. Most everybody has friends who work at all the competitors and a significant amount of people have worked at several of the big companies. So while everyone competes, I don't think hate is the right word.

Generally, the fanaticism in HN comments is much stronger than the sentiment of anyone actually working at these places.