How is having a significant number of users be served the wrong language for every site they visit, then having to navigate and create a profile and set the lan

How is having a significant number of users be served the wrong language for every site they visit, then having to navigate and create a profile and set the language for each site individually in a different way, in any way an acceptable solution either? If for historical reasons Accept-Language needs to pass through the OS locale, which is wrong and can't be changed, why not just standardize an optional User-Requested-Language(s) header, that only appears if the user explicitly sets it in the browser? The current solution is awful and improving it doesn't seem like rocket science but there seems to be zero interest in fixing it. Stuff like this is why closed platforms like Facebook probably have a brighter future than the open web.