> often taking the form of excessively literal readings that become weirdly and unhelpfully adversarial while failing to engage what the text was actually expressing

I see you, too, have seen people not understanding that Humbert Humbert is not supposed to be liked, and that the whole book is him trying to justify his actions. God, the number of people who misunderstand Lolita because they can't accept anything about it except at face value is way too high.

> I have a suspicion that readers who are that bad are not, in fact, extremely common, but are just, for whatever reason, unusually likely to engage in Web discussions

Sadly, bad readers are that common. I taught at a high school, and even some of the other teachers were bad readers, and most the students couldn't get anything but a very literal interpretation out of any text they read.