Users can just create a new account and rank back to jr member in a month due to no merit restrictions. These guys are most likely creating 100 accounts at a time and have plenty more for back up once 1 is tagged.
You are right. Perhaps it will be better if implement merit small require for jr. Members. I think it will help to prevent lot of spam from forum. As well as many people make sound about it include you, if I am not wrong. But still no respons from admin side. I believe it will parmanent solution for prevent spam. At least 2 or 3 merit require for upgrade Jr. Members.