But no one has demonstrated an actual operation that requires valid UTF-8. The reasoning is always circular: "I require valid UTF-8 because someone else requires valid UTF-8".
Eventually there should be an underlying operation which can only work on valid UTF-8, but that doesn't exist. UTF-8 was designed such that invalid data can be detected and handled, without affecting the meaning of valid subsequences in the same string.
But no one has demonstrated an actual operation that requires valid UTF-8. The reasoning is always circular: "I require valid UTF-8 because someone else requires valid UTF-8".
Eventually there should be an underlying operation which can only work on valid UTF-8, but that doesn't exist. UTF-8 was designed such that invalid data can be detected and handled, without affecting the meaning of valid subsequences in the same string.