there have been quite a few hub failures with the cheap RCGF engines where the wall thickness was around 2mm. these are smaller engines from around 20cc to 45cc and no idea what alloy was used.

it's not all about the power being transferred but HOW it's being transferred....a sharp hammering pulse every revolution.....constantly accelerating and decelerating. if the carb is out of tune that hammering can get much worse. and then on the other end a big stick that will never be perfectly balanced statically or dynamically and constantly fighting gyroscopic forces as well. a good comparison is how the sockets designed for use with impact wrenches have a much thicker wall even though the final torque being applied might be much less than with a regular ratchet handle.