I don’t mean that a culture needs to be imperialistic to be non-weak; but ‘imposition’ is something that happens internally as well(and is a fairly core function: we actually call it ‘acculturation’ when you do it to children).
It’s pretty rare indeed to find something you would call a ‘culture’ that doesn’t include some theories concerning just power distribution, behavioral expectations of various sorts of people within the culture(by age, sex, class, caste, etc.) Even in the absence of political power, these positions will usually be backed by strong social pressure on culture members(especially the ones with relatively little power). If a given culture group gets a taste of power, and isn’t specifically insular, greater levels of force and a willingness to demand compliance from non-members get pretty common.
Imperial enthusiasm/universalist aspirations/interest in evangelism vary widely(and many have little enough power that their level of interest is irrelevant); but a willingness to acculturate new members and lean on perceived deviants, apostates, etc. is much less variable. Exact demands vary, as does who gets the most pressure; and what constitutes “stepping out of line”; but even the most friendly or inward looking cultures tend to take a hard line when this is deemed to have happened.
