I believe that restricting new accounts to signature-less posting on starter boards, and only allowing them to post on the main boards once they had been awarded 5 merits ( say ) would be the simplest solution.
Yeah, I don't think we should restrict them 100% from being able to create threads anywhere but I wouldn't be against some sort of Newbie Jail coming back where maybe they can only create a thread in Beginners and Help and Meta at first or something. It's getting too much with thousands of people flocking here that are have no idea at all about bitcoin but are just here to earn by posting and it just leads to utterly mind-numbing crap being posted day after day: "what is bitcoin for you" "how did you hear about bitcoin/bitcointalk" "why is the price going up/down" "should I mine or trade?" etc etc every day and it just gets worse as time goes on. Just look at the mess that is in Off Topic and Politics because those two subs are the go-to boards for people who don't know about anything else. I don't think those two boards should be accessible to lower ranks because why would someone even come here just to discuss Politics in the first place?