It’s a fundamental element in most RPGs: Strength modifies hit chance and damage. From time to time, a few heretics claim that the main attribute for close combat should be speed, dexterity, or something like that, but the answer to these people is always the same:
“You are as ignorant as you are [probably] ugly. For a trained warrior, speed is strength, and strength is speed. The damage any object may cause is basically speed x mass, so the bigger and stronger you are, the faster you will hit, and the more brutal you will be.”
The idea that, somehow, a nimble fighter would beat a 240lb man probably comes from the same crazy hole that gave us Waif-fu and similar nonsense.