how was the current threshold derived? has there always been a newbie "wait period" or was it added after-the-fact and the parameters tweaked? it's something i've suggested to a few other forums i've come across that have spam issues.
Originally there was no restriction. For a very short time the limit was just 50 posts. Then the current time+posts restriction was put in place. These numbers work alright. If I wanted to stick with newbie restrictions forever, I'd probably add some more restrictions so people couldn't lurk for 4 hours and then post 5 posts in a few minutes.
It's planned to remove these newbie restrictions in the future, once the moderation system is improved. I don't like blocking drive-by contributors. It should require almost no effort for an unregistered user to post something. The low "barrier to contribution" is how 4chan and Wikipedia got so popular.
Yes, I agree with the drive-by contributor aspect, which is why I am going to request a pre-emptive whitelisting. I have spent who-knows-how-many hours anonymously lurking over quite a few months, but it wasn't until I had a problem with the mining app I use that I wanted to participate in a thread.
Same thing happened with wikipedia: I first contributed there in 2003, but didn't make any significant contributions until 2 years later.