I never understood people acting like downvoting is some huge crime or being downvoted is some great slight. It's a little arrow on a web site. It makes a number in a database go up or down by 1. I don't care how many points my comments score, and neither should anyone else. Speak your mind, or don't, and move on with life.
It's not about scoring imaginary internet points, it's about deciding what is and isn't acceptable in our community. For me the bar for "unacceptable content" is a lot higher than just "dislike."
As others have mentioned, if I disagree and think it's worth the time to engage, I'll respond and hopefully we have a fruitful discussion. Like/dislike doesn't really come into it. If I really dislike it I just close the tab or ignore the comment.
I was led to believe that the opposite was true: