On the old forum system, people started figuring out how to "hack" and post in closed threads, edit others' posts, post as others, post images (a big deal at the time), and other much crazier stuff (I'm looking at you, CashCrazed). Evil people would post corrupted threads (mostly pr0n) and heroes would construct other hacked threads (The Wedge) which blocked evil threads. A Society of Forum Secret Keepers grew, and sorta helped or prevented people from figuring stuff out. This Society constantly debated whether this stuff should be allowed or not. People started going to and posting in secret "hacked" areas of the boards.
Crazy stuff, and it eventually led to certain HTML being allowed on the old boards (without hacking).