The Colour and the Shape: Custom Fonts in System UI

Apple should give developers the ability to use embedded custom fonts in alerts, share sheets, action sheets, under-the-cell buttons, and so on. There’s no technical reason not to, and every philosophical reason why they should. If the concern is consistency, the right thing to do is set expectations and guidelines in the HIG, and enforce them in app review.

I think I understand the argument here, but please, god no.