I don't have a use case. I am saying that it requires zero effort to treat filenames as a big bag of bytes containing whatever, encoded however anyone wants them to be.
Anyone arguing for case-insensitivity has to both a) demonstrate that this is a source of confusion in the real world, by actual people using computers in UIs that exist today, rather than "when I think about it that's kind of weird because it doesn't behave like Windows" or hypothetical oh-dot-texts and b) come up with a better plan that handles the world outside of US ASCII.
Anyone arguing for case-insensitivity has to both a) demonstrate that this is a source of confusion in the real world, by actual people using computers in UIs that exist today, rather than "when I think about it that's kind of weird because it doesn't behave like Windows" or hypothetical oh-dot-texts and b) come up with a better plan that handles the world outside of US ASCII.