Confused by the wording of Leaverbuster by riot

Simply put, Can I be banned, for leaving, aram games What is the max penalty otherwise of wait times?

And why have I just heard about it today, when I logged on it asked me to type "I agree" when I have never had to before.. and to be honest I have dodged many aram games in the past.. Yet there are forum posts that date back to 2012 on it..

TY for the info.