About 5ish years ago, Matt set it that you can't delete your own posts in Gaming Discussion and General Chat because people were dicking around by making stupid posts and immediately deleting them so mods couldn't reprimand them, so that was his fix. It was never lifted since he made it that way, as far as I know. If you really want a post deleted, you can PM a mod when they're online they should delete for you.
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This is my sig until it stops being my sig.
Ce n'est pas une signature.
Mathemagician-in-training.
>tfw you will never have as many posts as bjw ;_;