Everything fits on one screen, the font size is much more bearable, there's no unnecessary columnization or links to other parts of the site.
It just gets out of the way.
.../140 -> test test test
.../141 -> My personal depression diary entry no.3 ...
But for 16px and up, which is what websites of today use, serifs are perfectly fine even on 1× displays (though sure, they’ll look better still on higher-DPI displays, but so will sans-serifs).
I should clarify that it depends on the font. Sans-serifs tend to have fairly even stroke width, but serifs tend to have more variable stroke width, and if the thin is too thin, you get a terrible font. That’s a common shortcoming of serif fonts, and Garamond demonstrates that, being quite unsuitable for screen use below 20px, maybe even 24px. Others like Georgia don’t suffer that weakness.
Georgia is a terribly underrated font. I'm sure it's heavily hinted to look good at small sizes, but even at large sizes it has an elegance that is lacking in e.g. Times Roman.
[1] https://developer.mozilla.org/en-US/docs/Web/CSS/@media/reso...
If I see default browser serif, my immediate thought is "either this is an amateur or something is broken."
Or just `font-family: serif` which will most commonly be Times New Roman or similar, but will be whatever we prefer for those few of us that set the default fonts.