Twitter has been playing with this type of thing for a long time (pre-Elon). I tried to DM a few people who say "DMs are open" in their profiles, and it wouldn't let me. I remember being frustrated because it didn't fail until I tried to hit 'send' — it let me sit there and compose/edit my message without telling me that it was going to refuse to send.

I found this odd and annoying, since I very rarely send DMs, am not a bot, and do not have bot-like behavior.