Then how about not including nostr DM in the clients? Fiatjaf removed DM from branle for that reason. Use other tools for this. Nostr is not for DM.

I suggested a DM nip that would improve the situation and that would work for group chat, too, sort of but I also think nostr might just not be the best tool for encrypted communication. Better improve the public message use-case than to stress client devs with more and more standards that are inferior than other existing tools.