@kitty cuz they can? People like power. If they are either trying to create a safe space or an echo chamber it will help to isolate their instance from dissenting opinions and statements.
@kitty well, first of all, if you are not self hosting then download (early and often) your contacts list. If people have freedom then when they are paying for the resources to run an instance then it is their bat, and ball and consequently their rules and choices, as long as they are not a government actor. While lists are great and all, but I am not sure that is how the federation works.