

in addition to what others said, it l matters who is making the rules.
in my own home i make my own rules and they are subject to my discretion and may change whenever I want. and even if someone is following all my stated rules if I don’t want them there, they aren’t allowed to be there.
following a community’s rules doesn’t guarantee anything and the person making the rules has a right to remove or keep whoever they want. you have no right or expectation to remain in a community if the community owner doesn’t want you there.
businesses and hoas and neighborhoods make the majority of their own rules but can be superseded by rules from the county, town, state, or federal government.
when a business runs afoul, a customer may bring a lawsuit to the higher authority. in lemmy communities, other than instance admins there are no higher authorities so you get what you get.
furthermore if we lived in a fully libertarian world where there were no higher authorities governing business (which is a closer analogy to lemmy) you would either have to deal with being discriminated against, or try to organize with other members of your community a boycott to pressure the business into behaving as you want through capitalism. you can do the same on lemmy. you can boycott a community or instance and try to guide others to better communities.
creeper