In primitive societies men were more easily killed in war while women were captured. This accounts even for purported "peaceful" hunter-gatherer societies, where wars always ended in genocides of men and boys, and capture of the females. Remember, this study accounts for our entire species' worth of history.
Current consumerist society is basically the 20th century. "Incels" did exist during the 18th century and prior, but were rare. For inceldom to exist, there must exist two conditions. Urbanised societies and free sexuality with birth control. Given that, a lot of the current incel population would probably have been killed by their village communities had they been born in medieval society.