> Like child abuse imagery

you would call that a filter, like spam, and of course it's essential and can be deployed in multiple points (before sending, between servers, at the client). Both users and server instance owners can have control of what they allow. There is little disagreement that these filters should exist, so i expect all server to implement them.

Censorship is about allowing e.g. governments to request takedowns globally. most servers will reject such lists.