The main problem isn't Starship with its six measly engines on a lower-gravity celestial body (e.g. faster lift-off). The main problem is the Super Heavy boost

The main problem isn't Starship with its six measly engines on a lower-gravity celestial body (e.g. faster lift-off). The main problem is the Super Heavy booster, tearing the ground apart with 33 engines at full thrust while struggling against 1 g downwards. This is a very Earth-specific phenomenon, because of our relatively high gravity. You can easily do a Single Stage to Orbit launch with just Starship on Moon, Mars, Europa etc. It is very likely that Super Heavy boosters will never leave the Earth.