Right. I call it the Hacker News Right-Side Effect (or should that be Rule, like the Off Side one ... :):

In many HN threads with lots of comments, at some point in the thread (and very often starting at or near the top), the comments successively veer off to the right, sometimes to a ridiculous extent, forcing rightmost comments into a thin vertical column that is a pain to read. And worse, the main topic of the OP is often not discussed much at all, since the majority of comments are about these minute inconsequential details, as you say above - and since these trivia subthreads tend to get upvoted the most.