Moreover, why do you only care about the downvotes? Why don't upvotes bother you? Something to think about :)
The parent post made an assertion, but did not really justify that assertion. Sure, it's easy to say that in some abstract sense "down votes don't matter". I believe that myself, in that sort of abstract / hand-wavy sense. But real life experience shows us that down votes do matter to people - at least some people, some times, in some situations. Why? I'm not a psychologist, so I'm not going to pretend to understand the deeper aspects of that. But it seems self evident to me that it's related to the other evolved responses we humans have, related to peer approval, social status, recognition, embarrassment, etc.
But _why_ does it feel kind of grating? Why does it frustate you?
In the specific case I mentioned, I think it's largely about the mismatch between expectations and perceived subjective sense of "right/wrong" and reality. I expect random throwaway comments that just say "taxation is theft" to get downvoted. But when I spend 30 minutes doing research, looking up citations, and crafting a carefully composed response to something, to try to make a point or provide a useful reference to help somebody and then that gets down voted, it triggers that instinctive "unfairness reaction" that we have. Or that's my approximate theory anyway.
Moreover, why do you only care about the downvotes?
I think because a downvote is a form of disapproval, and it's done in public, and it correlates to our desire to avoid being shamed / embarrassed, especially in front of others.
Of course I can understand the psychological part of it, but that's what I contest here.
You write an insightful message in a forum. Perhaps 5,000 people read it, 100 upvote it, 200 downvote it, and let's say that 5 reply with disagreement or trolling.
So in the end you find yourself frustrated with the 100 downvotes and the 5 trolls. It's irrational.
I can understand how people who profit from likes, upvotes and comments in forums and social media can care about their "Internet points". But for an individual person to care if their post has any kind of vote or to track the number of likes, sorry, I don't think that rationalizing it is any beneficial, productive, sensical.
This means on these platforms downvotes are a weaponised tool wielded by someone who can destroy the effort that went into post with but a mouse click.