The fact that someone is knowledgeable about a subject doesn't exempt them from being a constructive contributor to a discussion.

Additionally, no where was it "demanded that you explain in detail". I don't mean to be too blunt here, but there is quite a huge gap of comments between a detailed explanation and what you posted.

As an example: "There were a number of things incorrect in this post. The largest one of them was stating X when in fact Y. For more reading on it, look at Z."

And notably this response required fewer words than those spent defending your initial comment.

1. The proper question is "When a commenter is very wrong on a technical topic, is it net-positive for someone with expertise to point this out even if they don't contribute further?". I think the answer is obviously "yes". You seem to be more concerned with whether people are pulling their fair share, vs. being exempt/special, which I claim is the wrong question.

2. Effort scales with detail. The example comment you give is 3 times the effort, and I wouldn't have made the original comment if it required that much detail. My comment took me a few seconds to write, and merely tracking down a URL link for explanation would have made it not worth it.

3. Rebutting the N-th confused post on HN about dark matter doesn't interest me, but the meta point of what contributes to a discussion does interest me.

What you're writing shows you continue to miss the point.

I've engaged with the specifics of each of your points. We may disagree, but it's not because I misunderstood your claims.

As the official self appointed Em-Drive denier here, my recommendation is to provide more information in the comments. Sometimes it's difficult. Most commenters here are not experts in the particular field, but are curious. Sometimes it's better to center in the worst part of the comment if it has too many errors.

Sadly, I don't know enough cosmology and general relativity, so I use this approach to this problem https://xkcd.com/793/

I think that general relativity give minimal corrections in the scale of a galaxy, only some local corrections that are important near black holes and some spots. So it's enough [citation needed] to use Newtonian physics, perhaps with some correction near the galaxy center and perhaps a small effective field with the average distribution of matter.

To track an individual star during many galaxy revolutions it may be necessary to be more careful, specially if the stars pass near another star. But to have a good estimation of the rotation speed it is possible to almost ignore general relativity.

Question time: Do the current simulations in the area use special/general relativity corrections? Do you have a link to a recent paper? A link to a simulation program? [bonus point if the link points to the option page to enable/disable relativity or select the approximation method] Is there a Wikipedia page about this? [Most of the times the Wikipedia page is easier to understand than the paper.]

Apparently General Relativity alone could be enough to avoid the need for both Dark Matter and Dark Energy:

https://books.google.no/books?id=MBjkuQAoyZIC&pg=PA58&lpg=PA...

I didn't get that from the comment. Please post resume.