The Newbie restrictions make sense. Enough time to deter / make spamming more difficult, but not so much time or so many posts as to overly deter Newbies from joining and taking part in the Bitcoin community.
Care to explain how you determined not only that the rules are good, but also that the choice of 5 posts and 4 hours is optimal?
Do you know any other web site with such rules?
Do you know other web sites that have no such rules, but are, to your utter disbelief, still free of spam?