You get more content out of a discussion with your neighbor in 30s than that. Those comments are genuinely worthless, they don't talk about things like:
1) What are the parts of an inertial confinement fusion based system which are difficult and which are missing today and would need serious investment
2) What is the likelyhood that the power output observed here could double, or more with other scale factors?
3) What's the net system costs once a plant is made. Is the fuel cheap or expensive?
Etc. It's fine to be contrarian, but most of the contrariness on this most internet forums is of the most basic, shallow kind that is defeated in a moment by any serious thinking.
The short answer to being better? Posts with more in depth content. I seriously think HN should consider banning pithy one or two sentence posts "they still would only get 1/4 the power" you find all over the place.
Online discussions "between two people" merely mimic a conversation so the audience (of potentially thousands+ of people) can learn and be swayed.
Online conversations are inherently broadcast so the stakes are too high to acquiesce or make concessions for whomever's willing to actually take the bait and engage on "important" topics.
What could be done about that aside from expecting people to just... be better? I think the shape of these forums induces those kinds of comments, even if the community and moderators make a real effort to uphold higher standards. And I think if I encountered the same people in a different kind of forum then I might have a higher quality conversation. Heck, my own comments would probably be a lot more constructive!
Real world example of what I'm thinking: I have a neighbor over one fence who has very different political views to mine. We have perfectly civil conversations in which we're both actually really engaged and trying to understand each others' perspectives and experiences, and not just keeping the peace by avoiding difficult topics. It feels like effort we put into the conversation is rewarded.
I can't shake the idea that there might be "one weird trick" (okay, maybe a handful used together) that could make it more rewarding to put more effort into online conversations on forums like Hacker News or Reddit. One I've wanted to try for a while is to recreate something along the lines of Slashdot's moderation system, but with room for a meta-conversation to take place in "moderation space" (in which all community members could participate) and for there to be opportunities for people to refine their comments in response to feedback — and for doing so to be the norm.
Maybe it's not that simple. That's okay, too. But I've seen different moderation strategies around the web produce very different results, so it seems to me that there should be plenty of room for experimentation, and a lot to learn from doing so.