It'll cost the spammers to do so though. If signatures get removed from ranks (and thus activity), users are going to have to pay to get one and while a regular user might not have many issues paying 10-50$ for a sig for his only account (especially if he plans to actively participate in the forum), a spammer's is going to take the hit of the aforementioned 10-50$ for each of his accounts getting banned.
But theymos isn't agreeing to remove signatures from users, so the better find out alternatives, in this way you can ban shit posters forever and they'd never come back. Even if a user has multiple accounts shit posting, he would not mind paying those 10-50$ because he can earn that much in less than a month and then again he continue earning by shit posting at the same time. Ban the user's ID forever, even if they use VPN, then people won't have to waste their time on reporting useless shit posters.
And that's why I agree with hilariousandco's suggestion to make certain boards not count towards the post count or activity. Doesn't impact what content can be posted yet removes any incentive for posting there, aside from genuinely wanting to discuss the legitimacy of a project or participating in a bounty / bitcoin giveaway / etc.
Not making those sections not count for activity count would definitely help but this needs to be taken into consideration at the administration level. Until then people can only discuss about it, actions do speak louder than words.
Simply removing signatures from ranks would solve the alts issue as a person would have to pay cold hard cash for each account he wants to run a sig campaign on (and as previously mentioned, would suffer a direct monetary loss for each of his accounts getting banned). Considering the generally privacy-conscious crowd that seems to hang around here, I doubt the alt detection would do much as most people who want to hide their alts simply sign up with a VPN, proxy or Tor in the first place.
Exactly, so what I'm saying is that there is this thing which detects your original IP even if you use VPN or anything, so if you're banned, you cannot access your account/s even if you use VPN. Simple as that. If this feature gets implemented, then people won't have to fuss about shit posters.