Nice piece and I agree with most of your points. However, there is one thing about the security of (public) blockchains I feel most people get wrong: it is not the blockchain structure with hash pointers that ensures the security, it is the proof of work part. Hash pointer make blockchains tamper evident, but not tamper proof. PoW makes blockchains secure in terms of preventing rewriting of the history. I would like your and others’ comments on this.