This is true if you're writing a letter about a difficult topic.
For HN comments, 99.9% of the time, a short comment is a low effort one and should be disregarded.
on the other hand, when I see a long post here I assume it’s yet another ego-driven tirade and skip past it.
> yet another ego-driven tirade
I tried to recall the last time I saw what I felt was an ego-driven tirade on HN comments, and I'm currently drawing a blank. There's a lot of what's called "performative erudition", and there is the occasional lengthy diatribe, but I would call neither one of those ego-driven tirades.
long, low: copypasta; rant; sales; slop.
(brevity, purposeful /s).