This is not a blockchain. A blockchain needs a number of specific properties (see https://gist.github.com/joepie91/e49d2bdc9dfec4adc9da8a8434fd029b) to actually be a *blockchain*.
Your definition at the start of the article isn’t correct either;
> In more general terms, it’s a public database where new data are stored in a container called a block and are added to an immutable chain (hence blockchain) with data added in the past.
That describes a *public ledger*, not a blockchain. These are wildly different things. I feel like this article is based on a literal interpretation of the word “blockchain” without understanding the history or technical underpinnings of the concept.