The code blocks sometimes also cause horizontal scrollbars on desktop. And all they have to do is add one CSS rule (white-space:pre-wrap).

But apparently there's people who dislike wrapping code so much, that it's worth messing up the layout of a whole discussion even if only one comment has code in it (or by accident, even). Personally, I dislike horizontal scrolling much stronger (and I actually mildly prefer wrapping code, but that's taste, the horizontal scrolling is a big annoyance).