Why does every website want to load fonts at all anyway? Just use the built in ones.

In my case, to know that everyone is seeing the same website, optimised for legibility, and with every UI label fitting in its alloted space.

Bah, stop trying to control what the user sees. Let them optimize legibility by choosing their own fonts and sizes. The best legibility tool is reader mode anyway, which completely ignores your fonts and layouts.

I'm designing for the average user, not the average Hacker News commenter. This is why the website is beloved by its users.

Mostly for branding nonsense

I have tried some of the accessibility oriented easy to read fonts that are supposed to help with dyslexia but it's hard to justify that megabyte when I am also balancing accessibility of slow computers on bad networks

since this is coming from a "technical SEO consultant": how about website owners and businesses stop bloating their sites with (mostly useless) trackers and analytics scripts first, before worrying how fonts are _crippling_ their performance

As part of the system font stack, we no longer need -apple-system or BlinkMacSystemFont to select the default font on Apple devices.

You want to use system-ui to select the platform's UI font, which is San Francisco on Apple devices. Availability is about 95% [1].

[1]:https://caniuse.com/?search=system-ui

Scroll to the bottom of the severely overweight article.