This ☝️

Clients should allow Users to filter/mute by NIP05. No NIP05 then I don’t want to see your replies.

Put the onus on NIP05 providers to not allow their service to be abused by spammers lest all their community get filtered out, then spammers only have the option of doing it from their own domains which can more easily be blocked and will quickly cost too much to be worthwhile.