User blog comment:Rappy 4187/Technical Update: June 28, 2017/@comment-1537751-20170630143218/@comment-27345308-20170630161633

They made the feature so users don't crash the chat server by sending a lot of messages too fast. There's about one server handling all Wikia chats and if ten users are spamming a chat with the intent to crash it, everybody else's chat will crash too.

Being ratelimited when you weren't actually hitting the limits is a bug, not a feature.