I have tendencies to want to do this, but I choose to stop myself, to remember that random (hopefully) people on the Internet aren't necessarily more reliable than some random article on the Internet. It's valuable to check one's sources, but how many people actually check the source of some random upvoted commenter? How many people have the capacity to verify the veracity of convincing-sounding Hacker News comments?

Same. It happens often that the comments repudiate or at least undermine the article's claim. By the time I've read a few I've lost interest in said article.

You should read the articles. You'll find that a lot of the "repudiations" are less convincing, or at least less interesting.

(I didn't read this article.)

I make a point to never upvote without reading the article first. Only signal boost new information/insights not rehashes.