Anyone can have an off/clipless moment/whatever knocking a mech just enough for it do [potentially serious and expensive] damage. If you're always aware of rear mech alignment then good for you.. hope no one accidently knocks into you whilst parked up and forgets to tell you... On a serious note they offer very basic protection nothing more but it's something at least.But where does it end ?
Call me old fashioned, but I prefer to set my gears correctly so they don't overshoot.
Mine made an annoying rattling noise so had to go