The clean slate thing was specifically in reference to wiping the, then current, chat restrictions when they changed the punishment structure to the current 10 game chat restriction, 25 game chat restriction, 14 day ban, perma ban escalation. Basically the point was to get rid of the massive chat restriction build ups. This allowed people who had 100s or 1000s of games of chat restrictions to get end of season rewards if they didn't get punished between then and the end of the season. It didn't wipe the record of them being punished.