1. When Linux was "coming of age" (around the turn of the millennium), Windows security was really bad.
2. At the same time, there were far more Windows machines than Linux
3. #1 and #2 together made Windows such an attractive target, that exploits for Linux were less of a thing.
"not ok" by LGPL licence so an issue for games,etc that wanted closed source so people talked about it, but a malicious worm creator could definitely go there since they probably wouldn't care about (L)GPL compliance (remember Linus has always been very hard on patches not breaking userspace ABI's).
This was annoying for exploit authors as well. Like an early form of ASLR.
I remember an ad that showed someone who had painted themselves into a corner with paint the shade of purple that Sun used in its branding with the slogan something like "we have the way out."