As you'll see in my other comments (and articles on it), "blockchain" is better described as a field with a set of related goals for technology artifacts, rather than a specific data structure [1]. I frame it as: it has blockchain characteristics if it's decentralized, immutable, and assets [2].

This is a much healthier framing, because it doesn't constrain the goals to a particular approach (e.g. a particular data structure).

[1] https://blog.bigchaindb.com/blockchain-as-a-field-47c9f45894...

[2] https://blog.bigchaindb.com/three-blockchain-benefits-ae3a2a...