> the HTML and/or CSS have been run through a minifier The purpose of these tools is to make code hard to understand by the curious Whitespace is eliminated and variables are changed to unhelpful names.

No, usually the goal is to minimize bandwidth. Smaller files download faster. Readability does take a a hit, too, though. Honestly I'm more surprised if a site ISN'T minifying their code.

BTW - Chrome dev. tools has a "Pretty Print" option available available when you're viewing the source. It doesn't restore variable names but it does reformat the code to make it easier to follow. It's the { } icon at the bottom, to the left of the Line #, Column # text.