If I thought my own comment was downvote-worthy, I probably wouldn't have posted it

Right, but that doesn't necessarily mean you should upvote it. Comments like the one above, while they add to the discussion, are not on par with comments that also make good, clear arguments, cite sources, and link to relevant resources.

ETA: Yes, I do realize the tension between this and the notion that I wouldn't post something if I didn't think it was upvote-worthy. If everybody agrees with me on this stuff I'm going to have to go back and un-upvote a lot of my own comments.