So how does your hypothesis explain that these hypothetical other readers consistently read one statement and disagree with it, and then read another statement disagreeing with the first statement, and disagree with that also?

You're assuming that these hypothetical other readers downvote for disagreement. It's completely possible to read an internet argument and think the entire thing is just stupid/poor quality/not worth wasting time on.

Here are posts I have made, followed by their voted score, followed by the number of comments.

Is your assumption that quality of post is proportional to the amount of discussion under it? (Edit: I see that indeed it is.) That seems like a huge assumption, especially since many long exchanges spin off from nitpicks and tangents. Also, the post of yours that generated the most comments was also really long, and even then a fair chunk of the replies were the descendants of my gendered language nudge.