> inefficient ... pumping a whole countries worth of C02
Proof-of-Work blockchains are a strawman. Nobody in or out of the ecosystem thinks they should exist. They're a legacy technology sticking around on inertia; the mainframes to Proof-of-Stake's microcomputers.
> None of the applications can be properly decentralised. Your house deed stuff needs to be enshrined in law, enforced by police etc.
So? I didn't say anything about decentralization. I believe that these distributed-compute platforms that use signed append-only ledgers as shared storage ("blockchains") are a better way to do regular old centralized fin-tech. (Like I said above: security tokens. Those are embedded in a specific nation's regulatory environment!)
(See also: https://www.bankofcanada.ca/research/digital-currencies-and-...)
However, there is a very specific case that blockchains enable that traditional finance doesn't — and that's "multilateral agreement with no shared legal framework." E.g. a person in the US making a contract with a citizen of North Korea. If these two people get into a dispute, there's nothing their governments will do to arbitrate that agreement. But they can at least rely on technological mechanisms to enforce certain rules about what they can and cannot do to screw one-another over (e.g. requiring 2-of-3 multi-signature validation to remove value from an escrow holding account.)
> your NFT tickets need the venue to validate
They need a venue to validate. If one supplier is willing to take another supplier's "tickets", so to speak, then you now have an economy.
Let's say these NFTs are game licenses — if the Epic Games Store went under, Steam could say "we'll accept Epic Game Store licenses to download+activate games on Steam" as a PR move. Do that a couple of times, and now you have an economy of transferrable game licenses, maybe with an industry body that governs their issuance acceptance.
I'm not saying that this happens by default; but rather that this end-state is the point of the technology; and anything else people do with it is basically noise.