https://www.lesswrong.com/posts/vHSrtmr3EBohcw6t8/norms-of-membership-for-voluntary-groups

Guest Norms

The host can invite, or not invite, anyone she chooses, based on her preference. She doesn’t have to justify her preferences to anyone. Nobody is entitled to an invitation, and it’s very rude to complain about not being invited.

Guests can also choose to attend or not attend, based on their preferences, and they don’t have to justify their preferences to anyone either; it’s rude to complain or ask for justification when someone declines an invitation.

Personal relationships and subjective feelings, in particular, are totally legitimate reasons to include or exclude someone.

The atmosphere within the group is expected to be pleasant for everyone. If you don’t want to be asked to leave, you shouldn’t do things that will predictably bother people.

Hosts are expected to be kind and generous to guests; guests are expected to be kind and generous to the host and each other; the host is responsible for enforcing boundaries.

Criticizing other people at the gathering itself is taboo. You’re expected to do your critical/judgmental pruning outside the gathering, by deciding whom you will invite or whether you’ll attend.

We don’t expect that everyone will be invited to be a guest at every gathering, or that everyone will attend everything they’re invited to. It can be prestigious to be invited to some gatherings, and embarrassing to be asked to leave or passed over when you expected an invitation, but it’s normal to just not be invited to some things.