Here's the detailed explanation Mizal gave me. (Thanks, Mizal. I still appreciate it.)
Years ago, the site was flooded with retarded furry eight year olds who were all obsessed with Warrior Cats. All the games people put actual work into were being knocked off the new stories page by half a dozen or more fanfics a day--literally all just one identical format of join tribe, meet [opposite gender] cat, go hunting, have cat sex and kittens. And the authors would freak out and attack anyone leaving a comment that pointed out things like the lack of spelling, grammar, plot...
They were being obnoxious all over the forums as well, and this at a time when the only active admin didn't have full powers for banning people. When one of the original mods, JJJ did come back he tried to control it in various ways. We had a forum for roleplaying and other games back then, that had to have a bunch of rules added and was eventually removed because they were trying to do cringe preteen "flirting" while pretending to be cats and it was a fucking war crime to have to read it.
He put in the 48 hour delay between creating and publishing a storygame that we have now to help control the flood a little, but eventually it just went to a blanket ban because none of these kids would listen and none could be convinced their non existent "rights" weren't being trampled on.
At first mods just went in and unpublished all existing stories, but they were still being made at a steady rate, and we realized that those unpublished stories still showed up in Google results and were attracting more cat children who just obliviously went on to use the site as a litter box. For awhile it got so bad the site name was actually part of the Google autocomplete for "Warrior Cats game".
And so that's when the final solution was enacted, and anyone who remembers those days still has PTSD and just doesn't want to deal with that shit ever again. Even now, years later, an admin search for certain key words will still turn up a few new fanfics that slipped in like cockroaches while we had our backs turned.