Is spam like this more of a relay problem or client problem? Both?

I’m sure maintaining good filtering as a relay provider will save a lot of cost.

But as long as no one is following the accounts tied to those publishing porn is there work to do on the client side to recognise those same accounts so users can ask for those tagged accounts to be filtered out of replies and DMs?

What’s your sense of the separation of responsibility in the Nostr ecosystem?