It's something that I've seen in many forums, and I'm a bit embarrassed that I didn't think of suggesting it. 
In addition to what "hilariousandco" mentioned earlier, those forums (crypto or non crypto) aren't similar (in terms of goals, standards and the amount of spams) to this forum (you shouldn't include those with this forum in the same category, even if they're crypto forums as well). I think it would be a good idea, and it would save some of the clutter on the index page.
That won't result in any significant improvement (I see it as a short "pause", only).With regard to the comment about it becoming a large spamming thread - we already have several of those, and they serve absolutely no purpose whatsoever. Why aren't those deleted? At least an intro thread would serve a useful purpose.
Then what makes you think adding another thread for spammers (not labeling all of the "Newbies") to roam around, would be a good idea? If you know several spam threads, then simply report them.