I blow my hair out with a dryer and Denman brush whenever I press it myself these days. I'm trying to cut back cuz I don't wanna do it too often. This year is the most I've ever blow dried/pressed my hair out....
As far as how bad it is for your hair, the higher the heat you use, the more often you do it, the longer the dryer is held to your hair while doing it, the less heat protectant you use, and the less skilled you are at blow drying are all factors that would make it more detrimental to your hair.
Of coure there will always be some people who can practically put a torch to their head and their hair will still either look good, or rebound quickly...I am not one of those people.
I say all of this to say that, with blow drying, like straightening the hair, you have to find what works for you. Try not to overdue the heat temperature, use a good protectant, and most of all, monitor your ends...all things equal, if you experience more splits and dryness after blowdrying, then it's probably the blow drying affecting your hair, so either cut back or revise your technique and/or product(s).
Good luck