Depends. HN works best with Safari's minimum font size, which nicely brings all the fonts to a uniform, readable size. For every other site I use ZoomBySite to find the zoom level at which the layout starts working.
That's what OP was using, and someone else was suggesting to use a minimum font size instead. I wonder if there is a way to change the zoom level at the OS if everything is too small, not just the web browser, but that would defeat the purpose of having an hd screen.
Also does the zoom level in your browser affect the resolution of videos/images? It seems like it would.
Most OS have the possibility to adjust screen dot pitch (ppi, pixels per inch). Using a "high resolution" display (like my 23"@2048x1152, or an Apple "retina" display).
Technically, setting your font to be eg 14 points, should be an absolute size - the same font should be the same dimensions (in mm/inches) on all displays. Now, you probably hold your smartphone closer to your face than you sit to your 30" LCD screen -- so that might not really be what you want (same font size on your phone and on your desktop screen).
Additionally this only works for scalable graphics -- which is why Apple went trough such hoops to make retina displays usable -- quadruple the dot pitch on screens, and all icons and bitmaps become miniatures.
Personally I just use the browser zoom-function -- I find most sites use too small fonts, and end up with too wide text columns (which is somewhat alleviated by not browsing full screen, but in a "long" window).
On Windows, devs rarely care about DPI issues, largely because they either never heard about the problems, thought "oh my GUI abstraction will take care of it" or think that the market share of non-standard DPI settings is too low.
Yes. It's annoying. Asus has a 13-inch 1080p Windows 7 laptop and everything so tiny that it is basically unusable out of the box.
Android does not have this problem since devs always use dp (density independent pixel) as units of measurement and OEMs choose good DPI values when they are releasing devices.
Although less gracefully, iOS solves this problem too (by doubling the resolution and scaling everything by two).
