re: blockchain differences: I hear that Ethereum is planning to move to proof-of-stake, rather that proof-of-work, but I don't have an opinion on that. There may be other salient differences I'm unaware of.

It's the 'smart contracts' that I think are foolish.

Replacing the legal system with code only makes sense if all of the following obtain:

(a) the code is 100% bug-free (b/c accidents cannot be rewound)

(b) all code-writers are 100% honest (their code does what they say)

(c) all contract participants are 100% perfet code readers (so as to not enter into fraudulent contracts)

(Strictly speaking, only one of (b) and (c) needs to be true).

None of these conditions will ever obtain.