Limiting newbie participation is very harmful for a community. Newbie jail will never return: I consider the newbie-jail period to have been extremely damaging to the forum. When barriers to participation are too high, then the best people often just won't go to the trouble of joining, and the people who are willing to jump through the hoops are often people who aren't good for the community: people with nothing better to do, scammers, get-rick-quickers, etc. Having a permanent newbie jail policy would improve things a lot in the short-term, but would end up being a fatal poison to the community.
I'm constantly trying to figure out how cognitively sound Theymos was, to have realized that out of the worst places, good things could come. Every damn person had been in that position; so tell me, how you gonna feel if anyone listed you among the new-era newbies that don't seem to add any value to the community?
No restrictions! The ones we've got is enough already... Let 'em spread their tentacles and do more, they could override most of us even as older members. As for the ones that go around posting links and stuffs, a proper use of "report to moderator" button could save the day.