Yes I think you're right on most of this. Some forums have survived for sure and they will hopefully outlast reddit. Some did relocate to Reddit tho.
But I wasn't saying half the world is brought to any awareness, they're just potentially unwanted footfall in subreddits or something
That's fixed by skilled moderation. Good luck finding 20 people with enough experience in an advanced subject. If you don't have funds to motivate them to share their experience, it's likely a fool's errand. And why should anyone like that share if it's not appreciated by the plebs?