I’m not an anarchist myself, and I consider... policing to be a positive institution overall.
noway 
your whole post conflates hierarchical violence and distributed tyranny with anarchism. incredibly dishonest framing.
the people who had power were the patriarchs and patrons, 'the community' was free male citizens only. this excluded women, slaves and anyone who wasn't a citizen.
local patrons (oligarchs) would mobilize client networks as private armies to collect debts and exert local control. this wasn't limited to street violence, patron networks also dominated local legal systems.
patria potestas meant that households were formally domestic tyranny. heads of household had legal power of life and death over wives, children, and slaves.
none of this is anti-hierarchical or consensual. 'no formal police' just meant violence was privatized through patron-client networks and patriarchal households.
roman collegia were not mutual aid, they were hierarchical guilds with aristocratic patrons who had total control over the institution. they enforced trade monopolies and social conformity among members.
I may not agree with anarchist proposals as optimal, but I am often more than happy to lend a voice about whether they are functional
i think i'm fine without getting validation from the roman slave-state