The author seems to overlook one of the fundamental purposes of money. Which isn't too surprising given her background, but somewhat disappointing given the topic of her site. That is, she ignores the role of money as a unit of account.

Traditionally, something is considered money when it can fulfil three functions:

1) Act as a medium of trade

2) Act as a store of (economic) value

3) Act as a unit of account

The last is critically important in the modern context because one of the fundamental uses of money today is to measure economic wealth/income/activity/potential. Many commodities can act as #2. Many abstractions can act as #1. Few things act as all three.