I expect a tradition of discouraging both sides of such discussions would significantly reduce their impact.

While I usually share a similar sentiment, upon consideration I disagree with your prediction when it comes to the example conversation in question.

People explaining things to the Clueless is useful. Both to the person doing the explaining and anyone curious enough to read along. This is conditional on the people in the interaction having the patience to try to decipher the nature of the inferential distance try to break down the ideas into effective explanations of the concepts - including links to relevant resources. (This precludes cases where the conversation degenerates into bickering and excessive expressions of frustration.)

Trying to explain what is usually simply assumed - to a listener who is at least willing to communicate in good faith - can be a valuable experience to the one doing the explaining. It can encourage the re-examination of cached thoughts and force the tracing of the ideas back to the reasoning from first principles that caused you to believe them in the first place.

There are many conversations where downvoting both sides of a discussion is advisable, yet it isn't conversations with the "Clueless" that are the problem. It is conversations with Trolls, Dickheads and Debaters of Perfect Emptiness that need to go.