Currently, we have #beatmaps and #forum via Discord. Separating these by creating two irc channels helps people to keep updated if Discord is experiencing outages (such as DDOS). It can be helpful to track mapper and modders to log various beatmaps if they have finished some beatmap-related tasks.

#beatmaps serves as an alternative to #modhelp. They can highlight users by mentioning usernames in chat. Everyone should have access to this when discussing mapping-related.

#forums serve as a tracker for users what has posted, as we know.

Another reason is, #announce is solely used for new leaderboard positions. Not just that, but this serves as a milestone achievement, for example, a certain beatmap hit the first 1k, 10k, and even 1 million… should be announced