It's not a bad idea but it makes the site even more of a pain to moderate than it already is. Trust me, it's by and large a thankless task.
The moderation policy here is fairly relaxed, but when a warning is given to a member and not heeded then action is taken. As the bottom line reads "We almost always give warnings, but never to the same person twice."
Moderators already are accountable to the site admin, who ultimately lays down the rules. There is a mailing list to which all reported posts go that all moderators have visibility of. Furthermore, deleted posts leave an audit. As part of being accountable, deleted posts remain visible to admins and moderators, along with who deleted it, when and why.
We don't simply delete posts and ban people on a whim.