slightly OT because not tor related:
But how many legit registration of new users are there in a week or day?
My guess is there are fewer legit new users than successful spam attempts, right?
So if manuall work is necessary anyway, why not turn it around and only activate the legit ones on daily basis instead of being forced by the spammers to react more often?

Is it fisable to restrict new accounts to only sent a pm to admins or post in a special thread and ask for activation before posting anywhere else?