It probably falls under faulty comparison:
https://unicode.org/emoji/proposals.html#Faulty_Comparison
Their guidelines change, and it’s possible these emoji were added with old guidelines. They can’t remove old emoji, which means specific buildings like Tokyo Tower🗼is an emoji, even if they prohibit the addition of specific buildings nowadays.
The problem with having cryptocurrency as emoji is agreeing on the specification how it should be drawn, and also make it different enough from already existing emojis such as coin 🪙. It is not exactly a tangible thing.