The problem is that having a near system-wide locale setting is a bad idea; it necessarily causes friction because it is far less granular then it should be. Id

The problem is that having a near system-wide locale setting is a bad idea; it necessarily causes friction because it is far less granular then it should be. Ideally, the locale should be a property of some piece of content, if that content necessitates formatting or interpreting some underlying data whose presentation is locale-dependent, otherwise absent. The locale should not be determined by the OS or the browser since it would be reasonable for a user to want to use different locales for different applications and web pages (or pieces of content within web pages). Furthermore, I would argue that the very notion of user locale based localization by default is misguided, since it is fundamentally no different from automatic translation of content based on the users' UI language setting. It is a form of misrepresenting the content, though with things like dates you usually don't lose much information in the process.