C'mon. I know you're being mildly facetious, but "naysayers" and contributors aren't nearly so cleanly segregated. And debate often leads to important decisions that can't just be coded away.

Most of the time, the long discussions aren't about anything important. Nobody cares how you build your nuclear reactor, but everyone wants to debate the color of the bikeshed.

Sometimes they aren't, sometimes they are. Something about babies and bathwater. The ideal online debate platform would algorithmically marginalize bikeshedding.

"The ideal online debate platform would algorithmically marginalize bikeshedding."

That is a great sentence, in both senses.

It's hard to do, though YC does have several features for this, and they seem to work to some extent.

That's true, but it's easy to see the point at which a long discussion turns unproductive. Unfortunately, that's usually easiest in retrospect.