Didn't show up as tiny for me, but it's an absolutely horrible font for long texts: a) Missing serifs - which by itself is not critical, but makes it significantly worse when combined with b) Paper-thin weight, which is hard to read, and worsens on computer displays because antialiasing (regardless of subpixel or not) artifacts become much more visible and hence have more impact.
"Designer" most likely worked on his shiny Retina Macbook and forgot to take lower ppi displays into account. Which (unfortunately) are still the majority, and will continue to for quite some time.
I have a tool for moments like this. It takes the central article on a page and displays only it in a nicely formatted in-window pop-up. I use Firefox Reader, though Evernote's Clearly and Readability would both suffice. Pocket would work too.
As much as I love HN, the UI is clearly geared towards a list of links, not text such as lengthy comments – these are harder to read. Granted, not unreadable and with proper paragraphs done by the author good enough, but not quite optimal as well IMO.
