+1 for Marking them with implications, and I think it is currently the best route we can go for in this case, considering the pros we get can outweigh the cons nnt mentioned.
nonamethanks said:
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I don't mind taking care of the implications, but I'm afraid it would cause people to start creating tons of tags in advance without any upload just to discourage people from uploading from any obscure obvious AI prompt account they come across, and I don't know what volume of requests we'd get.
We could put a quick warning note on artist creation page to only create a new artist if you have a post you want to up.