Vibration wears servos especially. Depending on your receiver padding, it can kill the receiver, but usually only does that in flight, and you can blame the crash on something else.

And today we had a case of engine vibration pop the head off one engine bolt and the added vitration had the other three out before the guy recognized what was happening and got the airplane down. The guy showed me the airplane when I drove up. It was pretty amazing because he'd noticed the airplane acting funny and had tried to throttle back and it'd sorta done so but then gone back to WOT. Turns out the engine went very sour when it went to WOT, wasn't producing power but wouldn't shut off. And was held to the airplane by the cowl around the muffler, the throttle pushrod, and lousy power. Never seen one like that. But have seen engines fly off.

I guess I've seen about one instance a year since the 60s where the head was snapped of one or more engine bolts. Usually the ones that don't break off hold the engine to the mount for awhile. And you spot the engine shaking.

Beyond that, and the reasons already mentioned, no others come to mind.