But the problem isn't with the campaigns themselves; it's with the low-quality posters who get accepted into them.
That (campaign management) is not really the problem either. The real root is in the incentive model. The incentives currently encourage people to shitpost (in various ways) to make money. It's just simple as that. Loads of the shitposting is in a hidden format. E.g. a drama/opinion threads full of nothing, straws of nuances "sophistically" discussed for hundreds of posts. You can make "contributions" that are actually not interesting to anyone (and nobody reads them anyway). Walls of text, directly from brain to keyboard without any filtering or attempt at coherence. So many posts are just mindless blabbering, stating the obvious or stating some nuances or semi-irrelevant aspects/ideas about the subject.
So shortly, content is highly uninteresting, people just post and post and post but never really carefully read or dig in to the topics (at least in certain boards). Deeper thinking doesn't happen, because moving on to shitpost elsewhere is so much more easier and gets you more money.
Solutions? Change the incentive model, but how?
I wholeheartedly agree because I actively browse the "Bitcoin Discussion" and "Announcements" boards, often checking out what the latest gossip is on Bitcoin or researching what the latest projects are and whatnot. I usually see a lot of meaningless posts spammed containing single sentence responses like, "project will go straight to moon" or "which ico do I throw money at to earn lambo fast?". Enough shit posts like that can instantly ruin a thread or projects legitimacy and potential.
It's quite true that droves of people join when the market is on the up and up. I guess you have to learn to enjoy the few moments of peace while they last, at least until the next bull run, because before you know it, the forum will be flooded again with newbs and spam. As for the solution, modifying the incentive model does seem like the most relevant idea.