Exceptionally dumb arguments (or perspectives) need to be refuted, briefly and firmly, at the point where they're made.

They don't need to be carried away to a favorable audience and debated and dissected as if they are of substantial merit. Even if you say "wow this was super dumb", the fact that you even bothered to mention it lends it more implicit credence than is warranted.

The rational reason to do that would be to win easy points with your supporters. It's brilliant in-group signaling. But it's terrible for the "marketplace of ideas".