There is no reason to allow opening thread by newbie. Maybe only in help and beginner section, where they can ask for any help or answer to his question.
They need first to read and learn. It will be easy to boost his rank if they understand this forum.
Pretty much this. Tho, it might be good to allow them like 1-2 posts in other sections weekly, just because there can be someone who has the preknowledge and can actually start some valuable topic. But the main, mega thread, problem can be solved with urging the ones who start a topic to lock them after they've received the answer.