once a note goes out to multiple relays, you don't know who is actively replicating those relays, so they'll get everything the relay gets. then, that other entity has all the notes and may never delete them, they can in fact, put up a website that displays "all the deleted content on nostr", therefore, deleting is wrongly worded, because it can never be truly deleted. we simply cannot know, hence, thinking that it was indeed deleted is false assurance and is sure to come bite someone later on. it should be seen more as do_not_serve_this_please, but expect it to still appear somewhere.