If you want high-quality posts, remove the signatures campaigns from the forum.
While it works, it certainly not best solution and theymos most likely won't stop it. There are other ways such as signature only enabled if you received
x merit within last
y days.
Besides, newbie account still can be used to bump threads (on few boards), shill certain altcoin/ICO and report bounty hunting activity.
If we remove all the signatures then the ranks will become irrelevant because the newbie and hero members, both cannot have the
signatures.
Avatar? Shorter interval between posting? No PM limitation?