When I was in college, I used several (commercial) electrical enginerring CAD programs that ran on Linux. A quick Google reveals that most mechanical engineering CAD programs seem to be Windows-only (not even a Mac version). I have no idea why that is.
I think it's unfair to dismiss the Linux alternatives without at least explaining why you don't care for them. It just doesn't add any value to the discussion-- yet another post expressing an arbitrary opinion with no facts to back it. They may very well be behind, but if so, shouldn't we be helping them to catch up?