[randomswede]

"Blockchain" is basically just a Merkle tree with a branching factor extremely close to 1. That is, in and of itself, neithre inefficient nor bad.

However, pairing that with a proof-of-work consensus mechanism is incredibly inefficient, energy-consuming (requires at least 50% of all available compute to be engaged with the blockchain or risk bad actors taking over).

[nurettin]

AFAIK There is no application of Blockchain other than consensus. Do you know of any to justify this distinction? (also why merkle tree? looks like a plain old list to me, with very few exceptions while it is being distributed)

[randomswede]

Well, a degenerate Merkle tree is a list (any degenerate tree is a list). As a consensus mechanism, I could potentially think of many ways of getting that, but none that are both efficient and trustless.

As-is, the cryptocurrencies we've seen have all been incredibly wasteful and inefficient. Any that would be efficient, both energy-wise and for speed-of-transactions would most probably require ditching complete decentralisation and thus be unacceptable to hard-core ideologues in the "crypto space".

For a rough estimate of the "transactions per second" you'd need to be a global, practical, "we handle all transactions", we can do a rough estimate. There are, what, 6 * 10^9 people on the planet. At a conservative guess, each person does about one exconomic transaction per day. Let's assume that is approximately evenly distributed through each day. A day is 86400 seconds, that's close enough to 10^5 that we might as well use that. That gives us at a minimum 6k transactions per second to be viable for a single global electronic currency.