Reddit Bans Subreddits about Making Fun of Fat People, Neogaf, and others.

[IceForce]

I'm pretty sure mocking another user on here while in a user group is against the rules and can get that person moderated if it is reported.

"if it is reported" is the key point here. Moderators can't see into private usergroups anymore, and private usergroups are almost always comprised of groups of friends, - friends who are unlikely to report each other.

So, without a shadow of a doubt, "mocking" still happens, it just never gets reported.