Men being slightly stronger on average than women has a LOT to do with culture.
When I was a kid, girls weren't even allowed to do the same calisthenics in school. There was severe social opprobrium for women doing strength training, learning martial arts, etc.
This is one of the things about the patriarchy, the things it enforces are seen as natural. Women are put in clothes that limit their mobility, beauty standards demand frailness, etc.