Because to me, they seem like de facto "Agree and “Disagree” buttons, whether or not it was the intent.
That’s how I treat them. Maybe with a bit more nuance: I’ll upvote for something funny, informative things, or general good takes. I’ll downvote if someone has a bad take, is unnecessarily mean, or is generally incoherent.
If the comment doesn’t spark a reaction I just keep scrolling.
What you say and what you describe are not the same. Your explanation is literally how it was explained on the other site. So you are better than you think you are. =)
And I do it the same as you. Something I disagree with or don’t like but is reasonably argued and not mean or full of any -isms? No vote from me.