[wtallis]

To an unfortunately large degree, browsers and browser engines are simply not concerned with respecting the host platform's defaults and conventions. The browsers are here to replace (and reinvent) the host platforms, not integrate with them. Developers writing apps to run in a browser engine are more likely to care about their app looking the same across all devices and operating systems, even if their users may care more about the app following the same conventions as other apps on their platform of choice.

Edge getting this wrong is embarrassing for Microsoft, but is not at all surprising when you take into account how notoriously fractious Microsoft is and how unlikely it is that anyone in Microsoft could enforce a cohesive vision for UI standards to the extent of being able to make this a release blocker for Edge.