Requiring 10 merits for wearing signature may reduce the shitpost/spamming from meta only if the spammers/shitposters are here for maintaining the required posts. Cause there will be a significant downfall in signature bounty hunters.

If theymos implement this system, shitpost will be increased, because-
The problem arised (spamming meta) because of hunting merits actually. It has been increased decently after the new requirements applied. So, requiring 10 merits will make people more hungry for hunting merit which will result more spamming.

Right now, I have nothing to suggest. The only thing we can do- Recognise merit beggars and stop engaging with those. Don't merit a person in meta who is showing concern or writing post for having merit. Although it will be tough for most of the sMerit sender.
I will update once I get any idea.