@davidgerard @thomasfuchs The only legitimately impossible thing is reply restrictions. Those just... don't work under the Fedi model.

You can kinda approximate it by silently discarding stuff on your home instance, but replies get sent to everyone that follows a person so it'd defeat the point.

Basically:
- Alice on instance A is followed by Bob on Instance B and Carol on Instance C. Bob also follows Carol.
- Alice makes a status with the intent of preventing anyone on Instance C from replying (but not from showing up on Instance C).
- C's instance doesn't bother with respecting reply restrictions for whatever reason, so Carol responds to Alice's post since she's a recipient to Alice's posts.
- A's instance rejects the reply (as it should) but because Carol is also followed by Bob, B's instance will still ingest the reply, defeating the purpose of the reply restriction.

This goes for a lot of the fediverse's external moderation tools to be clear. They don't work nearly as cleanly as you expect them to, they just work "approximately". You *need* to keep in mind that every external instance is a possible hostile actor who can mess with your privacy and message settings on your statuses in any way they want to.