Interesting. One reason to do this could be to avoid the user’s os-level font or text-scaling settings from affecting this part of the site. Though it does seem pretty heavy handed and not in the spirit of accessibility.
Fascinating, never thought to try something like this. Gotta wonder what the benefits are here, one has to assume Apple's devs are totally inept.
TTFB optimization to the extreme? Cheaper to transfer than downloading an entire font first.