Merkle trees and consensus algorithms predate "blockchain." So far blockchain has very little to offer other than solutions to Sybil attacks that so far are net negative in externalities.

You are absolutely right! It’s accurate to say blockchains are a synthesis of other technologies, and solve for particular, narrow use cases.

That is useful, but not as generally useful as cryptocurrency advocates want you to believe.

> My grandfather hears “blockchain” and he assumes he is looking at a crypto scam.

As a first approximation he sounds like a wise man.

> They’re not just for cryptocurrencies.

Please tell me about the other use cases.

Your grandfather is not that dumb.