The Jedi use those breathing things that are only for the mouth, and Boba Fett in his healing tank only has the breathing tube for his mouth while he sleeps. Does he not even snore?
The water-up-the-nose thing is mostly the result of one accidentally breathing in while in water
Professional swimmers pinch it closed to not have to think about that but if you're already using a breathing apparatus that covers your mouth you'll likely consciously breathe through your mouth anyway
I have thought about this before too... My only examination is that this is the same universe where people hold immensely hot and powerful beams of glowing magic-ness without burning their face off, so I don't think normal logic applies. Fair question though.
