> the Bitcoin blockchain would not have it's current immutability properties if only its current users could access it. But that's simply not true. Interesting

> the Bitcoin blockchain would not have it's current immutability properties if only its current users could access it. But that's simply not true. Interesting point. But I think this evolves around what makes "private" and what not. Is a network of ~10.000 anonymous nodes "private" if you now close it? I guess it would be called "permissioned" and not "private". Further, my point is that when you would close the current network and disallow anyone to write and read from it, other than the currently online ~10.000 nodes, disallow new wallets and participants (making it private) you'd loose three things, essentially rendering the blockchain unusable: breaking it's immutability: * There would be no new miners. * There will be no increase in usabiltity: no future gain. These two things will logically cause centralisation of the existing mining. After all: no new miners can join, and only miners can drop out. A typical "private blockchain" so not one that started out public, grew large and then turned private, but one that starts out private, therefore has no need for PoW at all: it makes no sense, and adds no security that is not already there (through enforcements of access controls). Hence either the PoW is just nonense and (even more so) a waste of energy. Or it is left out. And a blockchain without a PoW is just a DAG tree. Or cryptographically signed logbook. Which can be useful in itself. But which is not a blockchain.