I don't agree that all injury is from bad form or the gymnast doing something wrong. Everyone's body is different and gymnastics puts a lot of stress on many body parts. Sometimes, the way your body is made can predispose you to certain injuries, or it may be that the body has not adapted quickly enough to a repetitive stress, especially if it was not introduced gradually.
For example, earlier this year my DD had a foot injury, an impingement in a foot joint. The physio thought it may have been caused by her increase in training hours, i.e. her body just wasn't used to it. She had to avoid some things, e.g. vault for a while, but once her foot recovered, she was able to train normally. This kind of overuse injury could probably be prevented by introducing new activities, or big increases in certain activities more gradually so that the body has more time to adapt.
Another example, is my DD's hamstring injury, although I suppose not technically an overuse injury, caused by her coach overstretching her. We think her hamstring was pre-disposed to injury through several factors. She is not naturally very flexible, she also had a pelvic rotation which was putting stress on the hamstring, which may have been caused by muscle imbalances, which may have been caused by unbalanced conditioning at the gym. That is, they do lots of conditioning for quads, hip flexors and abs, and very little for strenthening glutes and hamstrings, the front of the body gets stronger and shorter, the back of the body is weak and pulled out of proper position. Because of the weakness in her glutes, she compensates with her back muscles, which rotates her pelvis further.
I don't know much about overuse injuries such as stress fractures, but my feeling is that a lot of injury has to do with the training regime devised by the coach. I don't think all coaches are thinking enough about training for muscle balance, using mats and drills to reduce repetitive jarring, spacing out repetitions of certain activities to allow body parts time to recover, and so on. Just my humble opinion. I have very little experience in this area, but unfortunately seem to be learning the hard way through my daughter's injuries. I would be very interested to see the thoughts of experienced coaches, e.g. Dunno.