Blow drying can really impede the healthy growing of long hair. Of course every head of hair is different, and some hair types can withstand blow drying more than others.
However, generally speaking blow-dryers need to be used with caution.
My own personal experience with giving up heat styling in general has resulted in a difference like night and day with my hair. In my heat styling days, I would frequently have many split ends when my hair was not yet shoulder length. My hair is at least 8 inches longer than that now, and I don't yet have a split end. I imagine that as my hair gets longer again, splits will be inevitable, but right now, I am split-free.
There are reasons why heat is so dangerous that people don't sometimes don't take into consideration. If your blow dryer is blowing air hot enough to burn your skin, you know it's hot enough to scorch your hair. Skin heals. Hair doesn't. It will likely fray, then break off at the scorching point.
Too often people will put a hot dryer much closer to their hair than they would to their skin because obviously, your hair doesn't have nerves that could tell you, "ouch". If the blow dryer is too hot to use 6 inches away from your skin, then you can bet that it is too hot for using 6 inches from your hair.
Does this mean that under no circumstances can you use a blow dryer on your hair? That is not realistic for everyone, I well know. There will always be a time that you may need to use a blow dryer if the weather is cold and you have a wet head.
The key to using a blow dryer when necessary is to make sure that you have absorbed as much water from your hair as possible with an absorbent towel. When you use the blow dryer use a warm or cool setting (not hot) and hold the dryer well away from the hair. Do not attempt to dry your hair 100%. Stop the blow drying before it's absolutely dry. If you keep blow drying when your hair is already completely dry, you will dry your hair out far more than necessary.
Also, I know that many people have slightly wavy hair and blunt bangs. It's okay to tame them with a round brush and a blow dryer, but again, don't use a hot setting. A warm setting, finished by a blast of air will do the trick. While you may not be concerned with damaging your bangs, as they are trimmed so often, you never know when you may want to grow them out.
So the bottom line is to use common sense. And as with everything, moderation is the key.