You're conflating the two & ignoring the nuance @Keychat just explained. There's a difference in architecture between twitter & telephony. But if folks understand you when you tell them to "DM my cell" I guess it's a non-issue for you.

As I understood from @Keychat's evidence.. You need to tell users to Chat with you on Signal but not DM you for Privacy communications.. I guess it is a great starting point to schedule and improving our privacy on private chats..