The keyboard protocol is still using the same approach as roughly since the start of computing: The keyboard is a dumb device, reporting each mechanical button that's pressed. The computer is the intelligent device, translating those into characters.
There are some attempts that have made it into various places, e.g. there's a flag in the USB HID protocol to indicate the physical layout, be it US, or some other one. Except no manufacturer sets it, so no driver uses it.
But, what if we had a keyboard, courtesy of QMK and similar firmwares, that is substantially more intelligent? If the protocol allowed for it we'd be able to have such nice things as sending an "a", an "あ", or a "●" without any remapping to be done! In fact if the keyboard could send Unicode sequences we can do things that aren't possible by remapping, like sending characters from various scripts through a macro key without impacting any keypress since we have an immensely increased value space to work with.
