This is a silly criticism, as long as the concepts of "cryptocurrency as a decentralized idea" and "cryptocurrency as many people use it in practice" are described by a single word.

If the article is correct about "practicurrency", then you're responding to someone saying that it won't affect "decencurrency". One of them is indeed not a Scotsman. All you're saying is that the word has more than one definition for two wildly different things.