From the day that the ban feature was unveiled to decidedly mixed reviews six years ago (#msg-2361602), people have pointed to what appears to be a rather noteworthy inconsistency:
Moderators on a premium board must adhere to specific guidelines to remove any single post, but they can permanently ban the poster for any reason (or no reason) whatsoever.
An oddity, n'est-ce pas? Nevertheless, that argument didn't resonate with the Admin then, and I'm quite sure it doesn't now. As you may have noticed, iHub is teeming with raving lunatics, and from a purely Admin standpoint, the banning feature works well.