I like their method because it reminds me of Internet 1.0. Back when you couldn't just wander into forums haphazardly. Any forum worth it's salt and serves a purpose needs to vet potential contributors in order to maintain focus on the forum's mission. And it helps filter out the assholes. Whom you can spot by watching for complaints within their first five posts.
Being on way more forums than I care to be registered to I can say this is a pretty weak attempt at filtering the unwanted. I'm an asshole and won't deny it. I stated why I'm here.