Pinch-to-zoom works fine on HackerNews on an iPad, and the HackerNews font is nothing unusual.
Regarding HN being too wide, why don't you narrow your browser window?
Personally, I like the fact the traditional web design in which HN adjusts the line to screen width rather than imposing a width.
Its just that it ruins the experience on mobile devices because you can't resize the window and zooming doesn't reflow the text.
for what it's worth, I don't really have a problem with it. They provide an API and there are like 90 billion ycombinator mobile apps to choose from which do a better job.
Narrow my browser window because this one site makes it difficult to read? I could do that, or I could just use a content script and leave my browser at the width I prefer. I maximize my browser for distraction free reading.
I may not be understanding it, because I just maximized the window and I don't see any issue, really.
Down voted comments are supposed to be hard for everyone to read.
It would probably take a competent someone a few hours to fix the readability issues of this site but they just never get around to it.
Edit:
Here's a link to what all comments look like for me, even if they're downvoted:
http://dl.dropboxusercontent.com/s/v5zcn9n4vg4m3cn/2014-06-1...
I also disabled scores and voting because I dislike that stuff.
This is the home page:
http://dl.dropboxusercontent.com/s/sicqor50smsl4hx/2014-06-1...