[jfk13]

You may happen to like how system-ui looks on your system (macOS? Windows?); but do you have any idea what it looks like for the person reading your resume, perhaps on Linux with a custom theme, or on an Android device where the vendor chose to ship some brand-specific UI font? Or on a 5-yr old version of the OS, or on the version that'll be current 5 years in the future?

IMO system-ui is hardly ever a wise choice for content.

[zinekeller]

> Android device where the vendor chose to ship some brand-specific UI font

Chrome (and Android Webkit) hardcodes Roboto as the system-ui font (in such a way that both Samsung and Xiaomi devices (which both have font options) cannot touch), and Firefox brings its own font rendering which also hardcodes Roboto.

If the system-ui font of Linux is set to a silly one (according to your opinion), then the user-in-question would realise that they are the one who picked that font that you called silly, in other words they don't care about your opinion at all.

[djur]

If it is legible I don't care. If I can select a style a little bit more specific than "serif" or "sans-serif", that's great, as long as it degrades to something legible. I've yet to see a situation where free-flowing text or headings became illegible because the font changed. UI elements, sure.

[philistine]

It simply puts a bit more trust on the user than normal. And if your OS has a ridiculous system-UI font that can't handle paragraphs well, you have bigger problems than some website.