Sorry to have to say it, but I did tell you so.
Dart has many more members now, but less activity. Why?
1. Ubiquity
One member is every where. Post a debate and he is likely to take you up. Post a thread and he is likely to respond. Members here want to interact with people, not just one loony guy. Though he has not done anything specifically wrong, his ubiquity discourages activity on the board. And that is now showing.
2. Obsession.
One member with a "God does not exist" obsession derails every thread in the religion board. His reply to any topic is, "God does not exist". What if people want to discuss God? Is not the religion board for that purpose? This attitude is repeated on other boards with people obsessed with other subjects, like Trump haters on politics board, evolution deniers on the science board, etc. Obsessions discourage activity on the board. And that is now showing.
3. Militancy
Members whose first post to an innocuous comments are filled with bile and vitriol. Members are at a loss on how to respond to a first post with anger and insult that is frankly inexplicable. There are people on the politics board for example, who seem to think they own the board, and will lash out in ad-hom at anything that personally offends them. Militancy discourage activity on the board. And that is now showing.
4. Naysayers
Any path suggested. Any path whatsoever, is immediately opposed by the naysayers. Mods or owners who will not lead will leave the board in paralysis as the naysayers play tug-of-war. And when the mod or owner makes a decision, he will be accused of being an authoritarian. This will happen.
At some point, (possibly already past) hard decisions will have to be made. An old established board could possibly absorb such infectious personalities. But a new board cannot. It must be protected till it is strong enough to accommodate these things.
We have the history of countless boards before us. Let's not make the same mistakes again.