That is more or less the idea, but the article explains that some cryptocurrencies (like Bitcoin) should be called digital money. In the same way, gold is money, but a gold coin with a nominal value should be called credit. Here is an excerpt:
'Created in 2009 by Satoshi Nakamoto, Bitcoin is commonly called a decentralised digital currency. However, according to the present definition of money, Bitcoin is simply the first form of digital money, as opposed to credit that has been issued digitally. Both digital credit and digital money are accounting ledgers that are stored in networks of computers. In the case of credit, the network is centralised, meaning that the authenticity of the ledger is set by a single authority. This is typically a nation-state that decides what credit belongs to whom and how much of it can there be in circulation. By contrast, the authenticity of the Bitcoin ledger is decided by a cooperative process called proof-of-work [36]. Any computer that is connected to the internet is free to participate in the process by adhering to a certain protocol. The protocol rewards those ‘mining’ computers with new coins at a decreasing rate that mimics the scarcity of gold. At root, however, the proof-of-work is a mathematical solution to the problem of coordinating different computers on the internet, in the same way as money in general is a solution to the problem of coordinating different people in nature.'
What you missing is the fact to realize difference between crypto currencies and fiat currencies. Digital is just expression, fiat is digital long before bitcoin, people use paying cards for decades. Where is the difference? Of course in what kind of principles currency is using for generation, distribution and transactions. Bitcoin is the first crypto-digital-currency build on blockchain technology.