I hate them mostly? I've sent HTML emails before and they're a pain in the ass because they don't fully implement CSS. I've heard arguments that grid layouts are a step backwards because they put layout information back into HTML.

I'm not really a web designer so this isn't really my debate. I'm just pointing out that "HN does it" isn't really a strong argument. Something might be the best available option for some particular task but still not optimal for a whole host of reasons. The point remains <table> tags do carry semantic information so it's useful when possible to restrict them to situations where that semantic information is correct.

You haven't written HTML emails (cross-client) if you think Bootstrap' s grid and the kind of HTML you have to write for emails are comparable.

There is no such thing as Bootstrap div hell, that is utter nonsense.

If you used Bootstrap 3 seriously you'd also know there were LESS/Sass mixins for grids. No need to use divs with classes if you have that arbitrary dislike for genuinely useful presentational classes.