Earlier quoted context omitted.
> It should not be legal to advertise the possibility of messaging someone, if that someone will not be able to receive the message. Unless I'm misinterpreting what you're saying, you seem to be saying that shadowbans should be illegal. Or at least, I don't see how any law that would prevent shadow delivery wouldn't prevent shadowbans. So I think we'll have to agree to disagree.
Would fedex shadowban be ok too? They take parcels, give tracking numbers, but those specific persons never receive anything. Tracking is always stuck on "parcel enroute". edit: clarified wording, to make it clear that fedex shadowban is a hypothetical situation
There is no such "theft of information" for failing to route a data packet, nor should there be for obvious reasons.
Better analogy would be if a newspaper took money to run my ad but never ran it. Also theft, or at least try-able in civil court for failure to render service.
... But if they take a message from me, for free, on the understanding they'll route it and never route it? Much, much grayer legally. I have to prove harm and that they had a legal duty they abrogated. Neither are obvious regarding Facebook DMs.