Yes, there are always two sides to things.
So, how about the idea of write-restricted areas that are accessible (for posting) only by invitation or, as was suggested above by Jet Cash, only for accounts with a certain rank?
I'd like to suggest a third alternative to use the number of merits received, instead of the rank / total number of merits. I've seen posts from hero and legendary members that don't pass muster, and those individuals have actually not received any merits, aside from the initial allocation. Although I have no idea how much effort this would take to implement, I can't imaging it would be too difficult. And since awarded merits are to a large extent (although not completely) reflective of the quality of the contributions, it seems like an appropriate yardstick.
And using the awarded merits as an entry point to the write-restricted areas would not materially affect legitimate users. Since users can still read the forums, they are not loosing out on the content. But only those who have demonstrated in the open areas that they can provide valuable input and have been recognized as doing so by having received merits, can start contributing actively to those write-restricted areas. Whether this applies to sections in the forum, or at the thread level is perhaps a secondary question, but I can't see how this would not lift the quality, while not being too restrictive either.
Any thoughts?
I don't think it's a terrible suggestion. It really all depends on what sections will be rank/merit restricted. If we limit all Bitcoin related sections and only allow people to rank up in the altcoin, Beginners, and local boards we'll just see an increase of spam there. Yes, it might be restricted to one section, but that just means whoever is moderating that section or frequents those sections will be overwhelmed with low quality posts and people attempting to get merits by making their poor quality posts look constructive or of an outstanding quality.
Possibly, we could make merits spendable to unlock certain sections or certain threads. If someone is willing to spend 1 merit to unlock a thread then you would probably expect them to at least try and get that merit back by posting in that thread. Although, this is assuming that everyone cares about merits not everyone will and the likelihood not many people make enough posts let alone quality posts to get enough merit to do this. I don't think this is necessary and is adding a sort of pay wall behind threads which not every post needs to be constructive.
I don't think this is a good idea side wide, but could be an option for those people who make self moderated threads and want the discussion to be of high quality. They wouldn't receive the merit it would just be lost forever to avoid abuse. This would also have it's drawbacks including less sMerits being spent on quality posts, although we could just leave that up to the merit sources in the future when there's a lot more of them around.