But isn't that exactly the point? That decision, with Bitcoin, is distributed and decentralized. We've always been able to decide how to add an element to the

But isn't that exactly the point? That decision, with Bitcoin, is distributed and decentralized. We've always been able to decide how to add an element to the end of a (possibly cryptographically secure) chain of blocks. What separates the two definitions of blockchain in this thread is exactly the distributed and decentralized choosing of the top block.