Thomas, I’m not sure what you mean when you say that certificates are free. Self-signed certs are free, but only situationally useful in a business context. Let’s Encrypt certs are free, but not usable in all contexts. GoDaddy, Namecheap, and Verisign will still gladly charge $50-$1500 for certs will various features like $50/SAN, and extended validation. If you want to terminate TLS at an AWS managed edge resource, the happy path is ACM. These are “free”, but arguably you’re paying for the cert with the load balancer or edge resource.

There’s no difference between a blockchain and a cryptographically secure write ahead log, indeed that is how blockchains are defined. Perhaps you assumed that I meant cryptocurrency when I said blockchain? I did not.

(Sorry for the delayed reply.)