Many years ago I thought the highlighted text was a light hearted joke. Now I see what it is actually quite serious. (And now I understand why, among all people, a Japanese philosopher brought up the issue)

I personally think Unicode didn't go essentialist enough though. There's lots of obscure CJK characters in unicode that, when you look up a dictionary, just says it's another form of a common character. What I heard from people in the know was that the CJK committee basically made an exception for the Japanese because they were threatening to withdraw from the Unicode effort unless their demands were met, and for the most part they got what they wanted.

The "Chinese versus Japanese ideographs are the same characters, drawn in two different fonts" is actually a minority of those cases, which I personally interpret as clerical errors instead of a philosophical disagreement.

For example if Unicode were actually thorough with the essentialist philosophy, 關 and 関 would have the same code point.