I like the merit points idea very much.
My suggestion:
I would say
fixing a minimum char limits in some of the sections of forum will lower down huge no.of spammy posts that altcoin discussion bumpers or spammers make like:
Wow

...Interesting project.
However I think it should be implemented on only in some of the sections where we often find these kind of posts as spammy.
Not really, i've seen plenty of spammers simply spouting more nonsense just so they have 75-100 chars. They will just adapt and make their sentences a bit longer with even more nonsense.
I really doubt that that is going to solve anything.
- lock off-topic/low-quality Discussion.
- remove Other languages/locations Board.
- make post quality trust (like normal trust).
Or simply remove the potential activity from Offtopic/Politics/Local Boards.