I'm tired of explaining this but flight-paths and gliders function very differently to flying mounts. You also need to learn how to not just think of extremes. If Blizzard say a certain level of convenience is too much that is different to saying that all forms of convenience ever are bad.
I think most players would agree that an ability which could one-shot any raid boss would be a bad idea, but that doesn't mean that all damage causing abilities are bad. The former is merely an example of too much damage, which is what makes it bad. That is not saying that any damage is bad.