Isn't it the job of the user agent to have options to override the choices of a website? Otherwise, the subset of "fonts everybody is sure to have" is just too small.

Why not let everybody have websites look how they want them to look? I'm kinda sad this vision gets so little attention, that instead we all try to push our vision on our visitors. Even if the web turns app platform.. just like we have configurable desktop managers, browser could still let everybody customize how websites look - if only websites could stop with the "story telling" and "experiences", and concentrated on utility and information. We're too addicted too shiny for our own good already.