You're looking at it from the perspective of a chat Participant instead of an Owner/Administrator.

For the owners+admins, the other alternatives of IRC, email mailing lists, forum software like vBulletin, phpBB, etc require extra work of provisioning a server and maintaining it.

From the perspective of the chat topic owner, Discord is the simpler than any of the above. Just click "Add A Server (+)" and start sending out invites in seconds. (https://support.discord.com/hc/en-us/articles/204849977-How-...)

In other words, the tradeoff is it's more hassle for some participants (like you) but it's less hassle for the topic administrator.

Another feature that's important to some Administrators that's not easily available on a self-hosted IRC server is blocking bots or lower-quality participants via Discord's "Verification Level": https://support.discord.com/hc/en-us/articles/216679607-Veri...

Turning that knob will also annoy some potential participants.

EDIT ADD a link to help illustrate the reply about "RBAC" implemented in Discord: https://support.discord.com/hc/en-us/articles/214836687-Disc...