dynamic, done properly, is okay. it is just that no one has the time or patience to really do it properly.
i took modern dance to help with my athletic performance, and you do about 40 minuites of progressive dynamic warmup before you really push yourself. this isn't going straight into those herky-jerky leg swings. those are dumb.
i know former martial artists and gymnasts who have problems now since they over-developed their flexibility.
you can be too flexible, especially if you are not stretching in a balanced manner. if you are always doing hamstring stretches, but never stretch your hip flexors, you are setting yourself up for low back issues.