I think in all of this you're forgetting the basic premise of a job board which is matching supply with demand. Curation is a part of maintaining high quality in the board, yes, but there's still the need for enough supply to make people come to the board. In your description above, there's nothing unique.

If you are going to curate the supply by hand, that to me isn't appealing as it's not sustainable. If I post a role on the board and the board becomes stagnant because your ability to curate for free goes away, I wasted my time posting there.

Likewise, if I were a developer looking on your site and the listings are stale, I'm going to turn away.

What unique advantage does your board offer that no other board offers?