How do you prove a unicode character is unused? Look at every database field in the entire world? Every book someone has ever typed on a computer and printed? See what fonts include them or don't?
You can't define what an unused character looks like once it's in the standard... even less if it's already available on almost every modern computer.
People have already used these "ghost characters" when describing them, as jokes in their online handles, etc... This article and now this comment include "妛" which is one such character.
Furthermore, how would you even remove them? Tell all font authors "unicode point X now shouldn't be included in your font"... why would they ever bother to remove something from a font?
And what would be the benefit? Unicode offers enough codepoints that there's plenty of space left over for whatever garbage you wish to include, like new emojis and super-astral-aether-planar characters.
You can't define what an unused character looks like once it's in the standard... even less if it's already available on almost every modern computer.
People have already used these "ghost characters" when describing them, as jokes in their online handles, etc... This article and now this comment include "妛" which is one such character.
Furthermore, how would you even remove them? Tell all font authors "unicode point X now shouldn't be included in your font"... why would they ever bother to remove something from a font?
And what would be the benefit? Unicode offers enough codepoints that there's plenty of space left over for whatever garbage you wish to include, like new emojis and super-astral-aether-planar characters.