Sending a large number of unsolicited DM messages in a short span of time.

So basically I was doing join4join (join for join), And my main account got disabled because I have sent a lot of messages in a short time. And the messages were about to join for join like I join someone's server and he/she joins my server.

Why accounts get disabled because of doing join for join? I don't think accounts should be disabled for this reason because there is nothing wrong people do the rules of that break.