Some do. Not like in the old days. Apple is still the tool of choice for many, but any more, it's a matter of preference and not one that is grounded in performance.
It's been kind of fun to see the shift from Apple to PC, particularly among younger designers. I think (although this is speculation) that the shift is less about bucking tradition and more because the younger designers also tend to be gamers, and the Mac is crap for gaming. The engine that makes a PC great for gaming also makes it a workhorse, particularly for video and audio editing.
Of course, some video editors still use Final Cut Pro, but Adobe Premier and AfterEffects have cut into that stranglehold significantly.