Thanks for this simple but yet helpful information, many of us don't actually know what the so talked about "newbie jail" was until now.

And from the description on the quoted text above, I personally think that bringing that back will be really harsh on the newbies having in mind that the introduction of the merit system already does a great job in limiting spammers from ever leaving the newbie rank to advance to the next.
Also, introducing or bringing back the newbie jail will not only put the newbies to jail but also in the long term, put the growth of the forum to jail too, as this will ultimately deter or discourage new members from joining the forum, and some of this new members potentially can be the great posters the forum needs.
So, I personally advice against bringing the newbie jail back.