> or simply because they don't care about handling Linux correctly and the least common denominator requires shipping everything with the application.
There is also the fragmentation that makes handling things correctly harder. From the perspective of the software vendor "Desktop Linux" is a blip in the radar, and a very fragmented one. (How many Fedora, Ubuntu, Suse, Debian etc versions are there to test against?)
The software vendor can rationally decide that there will be less users hit by a bug if they put even more resources testing it on Windows and MAC/OS than trying to test things on this large matrix of different Linux distributions and all their versions in use.