The API still supports using the chat command, and users can add their own code to run dnd if they want, but we don't support the previous logic we used to have for it.
The change could have just been for QoL for normal users, but it could have also been done for other reasons, so it's not worth having the bot toggle it multiple times to try and figure out the state of it, as there's no nice way to handle the case when a user re-attaches the bot and dnd was already set.
For now, users can /dnd once per client startup manually as it'll keep until they restart the client.