It's a trade-off. Depth-first isn't always better, some tangents get ignored, but often one can craft a single solid reply that addresses the points raised by

It's a trade-off. Depth-first isn't always better, some tangents get ignored, but often one can craft a single solid reply that addresses the points raised by many different people in one go, keeping the discussion on-track. I think in fact this is a more common scenario in real life conversations.