—⁂—
But as a consumer of the web, I personally don’t actually need to worry about these things any more, because I have my browser set to use my chosen sans-serif, serif and monospace faces (Equity, Concourse, Triplicate), and you can too! ① Use Firefox. Other browsers may have something similar; dunno; but Firefox is good anyway. ② Settings (about:preferences) → Fonts → Advanced → untick “Allow pages to choose their own fonts, instead of your selections above”.
I started doing this a few months back as a week-long experiment, and found it so significantly improved the web that I’m not going back. (It did feel a little strange for a few days, as Concourse is a somewhat narrower sans-serif than the likes of Arial, but that’s about the specific fonts that I chose. Now it’s just perfectly natural.)
I have experienced a very few icon-font related breakages, about which I wrote yesterday at https://news.ycombinator.com/item?id=31540234, but it’s surprisingly few given how popular the technique was for a few years. I also get a fair bit of bonus unintended serif from people that have neglected to add a generic font family fallback, or misspelled it (e.g. sans or "sans-serif" (quoted) instead of sans-serif), so that it falls back to the global default, which I have left as a serif.