I do have a high DPI display, and HN is ridiculously tiny without manually overriding, because it's setting text size in pixels instead of points, for no good reason. It doesn't make any sense. View source shows:

    line-height:12pt; height:10px;

Why use device independent units for line-height, but not the text itself?

Might be an age issue. When you get older, small font sizes are problematic. It's rude of sites to use them, IMO.

My "eyesight issue" is being older than 40 ha! It'll happen to you too youngster!

I have a 123ppi display, normal is ok but I have it zoomed out to 80 or 90%.

People are different, so it's good to have font size and zoom options. Some can go bigger, some can go smaller. I use 80% on a lot of sites, and an extension called 'Zoom Page WE' to remember the settings.