[aprilnya]

But you’re not distributing the font. You’re not doing anything bad. “font-family: ‘Copyrighted Font’” is not distributing the font, and so is not copyright infringement, you’re just telling the browser to use it if it’s already there.

Disclaimer: Not legal advice

[tatersolid]

You’re correct that so long as you don’t serve or otherwise distribute the font files or a derivation the licensing doesn’t matter. But my comment specifically referred to the “they are all permissively licensed” portion which I quoted.

San Francisco, Segoe, and many other OS-included fonts have commercial proprietary licenses, not permissive licenses as the GGP post claimed. Try to serve San Francisco WOFF2 files as a font-family src on your site and see how Apple’s lawyers react.