That would mean that Zoë (spelt with U+0065 Latin Small Letter E followed by U+0308 Combining Diaeresis) wouldn’t match Zoë (spelt with U+00EB Latin Small Lette

That would mean that Zoë (spelt with U+0065 Latin Small Letter E followed by U+0308 Combining Diaeresis) wouldn’t match Zoë (spelt with U+00EB Latin Small Letter E with Diaeresis) even though they are the same name that just happen to be typed in on different platforms. Names exist at a different level of abstraction to binary and it’s a mistake to treat them as binary.