I believe telling a user not to DM me on this npub that shows their WoT with me or to not DM me on a currently familiar app but to download a new app, create a new account and add a secondary npub for me, is an extremely bad user experience and will lead to scammers harming users.
The key is to make Nostr more simple for the masses, not overly complicated.
I want a dedicated chat app very badly, but I'm not going to put new users through these hurdles to just DM me. There has to be a better way that has a nice marriage of UX and security.