Earlier quoted context omitted.
Some of the best HN has to offer in terms of interesting and thought provoking discussion is on generic tangents, and so long as the discussion remains civil and contained to those threads concerning it I see no reason to discourage it for being discussed.
I know how unsatisfying this is going to sound, but: this is a point on which we just have to pull rank. It's our job to foster the kind of site where signal/noise ratio doesn't completely suck, and many years of experience have taught us that generic tangents lead to low-quality discussions that grow like weeds.
(I really think there are lots of comments that are "blatantly illiterate", in that they respond to a meaning that is just obviously not in the parent. I guess that only kind of breaks the assume good faith guideline, as they are missing the meaning rather than mischaracterizing it.)
The point of the question is whether the userbase has been trained to respond aggressively to only a subset of low signal comments.