one reason is you need Ubuntu 16 to run these cards at there best, the problem and that's on AMD some cards still don't have AMDPROGPU drivers support for Ubuntu 16 once they do we will probable see a Linux version of CM . and it's not worth it to run two different version of CM in Linux form one with Ubuntu 16 and one with Ubuntu 14 , I'm sure he would use 14 over 15 i wouldn't, i would use 15 it seems more stable then 14 but that's  me, all because of AMD driver support while the windows drivers support all cards  and windows version but a few that no long have a use or are actually sold as new and may be no win xp support.

I don't care much for Linux either ,windows is so much easier to use . but I do like to use Linux on PI type PC over the windows version for PI type PC.