A complete system that destroys spam would end the race. WoT is part of that, but it needs to be augmented with a bootstrap mechanism. The narrow gate into the network would be either social onboarding, or some kind of expiring proof of humanity (captchas attestations by a trusted provider for example). 

 indeed, the onramp is the primary weakness of WoT 

 You can't distinguish spam from stupidity. We should focus on mass-spam. Every operator knows that fucking script-kiddies. Have you relay ops tried IP blacklisting against the reply-guy?