I agree with you that your definition is what we should define a blockchain as, as Natamoto defined it. However, I'm afraid to say probably the majority of companies that claim they use blockchain probably use something very close to Git instead, or even just a digital signature or a hash function. Seriously, it's ridiculous.

Imagine if Google called certificate transparency blockchain? Journalists would lose their shit. Such an easy article to write. In fact, Google explicitly say on their website that they're kinda against the hype: http://www.certificate-transparency.org/general-transparency "These technologies are strongly related to the much-hyped blockchain. The reality, of course, is that there isn't a "the" blockchain, and that decentralisation is not always the answer. We are not making "the" blockchain, and we do not claim to support decentralisation."

I'll never forget my first job the business people wanted to investigate "the blockchain" and the yes men came up with a bunch of PoCs. I just asked "how is this different to Git?" Such an awkward moment.