Unless you put in some efforts in what you write and just shitting on spam threads won't get you any merit and yes you will be stuck as Jr member. For that you need to blame yourself and not the merit system and its not even funny in any way.
Likewise I agree to your point on Local boards. Before when people had terrible grammar or zero English skills they were suggested to stick to their local boards for any information. But now that won't be the case as a newbie will be stuck as a Jr member even after 240 activity due to the lack of merit providers in the local boards or the board being a dead horses paradise. And everyone would want to rank up at least for trust sake. Though merits has its flaws it has helped on lot on the overall outcome of many threads. Lot of posts are actually meaningful and people putting in effort.
I wouldn't be surprised if De-Merits were introduced in the future also stated by Theymos himself. That would bring chaos across META.
Its already available. How do you think I got my first merit? Here's one such thread,
https://bitcointalksearch.org/topic/learn-from-arts-old-topic-name-was-smerit-for-art-2957836
These things make the forum even more enjoyable.