Some Linux people were saying "let's screw Solaris" first and Sun people are only human so that's the result.
[citation needed]
Reaching feature parity and taking Solaris' market share was an often cited goal by people in the Linux community, and one they achieved.
That said, I don't remember much actual hate directed at Sun in the way that Microsoft got. As far as companies go, Sun was a better member of the UNIX community than most.