I was all for writing long comments sharing my experience but the prevailing attitude on HN is "experts don't matter" and "covid vaccines don't work". No amount of additional contextual knowledge or explication will help those users (and I am exceptionally concerned by the latter).
I often extrapolate but sometimes, all that needs to be said is a single sentence, because it achieves my goal.
Ok, but for good posts, your goal needs to also take readers into account.
I'd be careful about any generalizations concerning the "prevailing attitude on HN". People routinely (I would almost say invariably) fall prey to false feelings of generality about this, because the annoying responses one encounters inflict a much greater impression on one's memory than anything else one encounters. I've written about this a lot, which may (or may not) be useful.
I think you must certainly have fallen prey to this bias, because "covid vaccines don't work" is extremely far from a prevailing attitude on HN. Such comments do appear, though, even though they're a tiny minority, and these no doubt make an outsize impression.
I often extrapolate but sometimes, all that needs to be said is a single sentence, because it achieves my goal.