Hunter-gatherer cultures, depending on environment, can (and have been observed to) have fairly high degrees of equality. If humans are the apex predator and aren't fighting each other, that men are physically stronger isn't critically important as long as the culture is that they don't use that in a domineering way.

Most farming doesn't require male levels of strength just to survive. It helps, sometimes, but persistence does too. Rather, if you farm, then you tend to store things of value rather than just finding them when you need them. If you store things of value, others might want to take them. To protect them, strength is extremely important. It is probably not coincidental that the transition to agriculture and the transition to war and the transition to patriarchal organization all happened at (very) roughly the same time in prehistory.