Take a piece of thin metal and fold it/unfold it a few times and it will probably break or at the least be weakened. Same reason airplane pa els need replaced after a certain amount of time the metal fatigues from pressurization and then being depressurized. Rocking a stem would seem to fatigue the hinge similarly. I think there are mountains from mole hills being made but you never know when your luck may run out, and it only takes one time for you to regret it. Just stay vigilant I think is what people here are trying to get across.