PoW is leader based consensus. It’s slow and can’t handle millions of simultaneous payments. Why do new distributed ledger technologies still prefer to use it, when there are other, far faster consensus algorithms out there?
> More seriously, if the name of the game is efficiency then a distributed ledger isn't the answer.
And if you're only looking for immutability, then time-stamping is already good enough (and available since the late 90s or so). I suppose you can use a Merkle tree and then proceed to put "Blockchain" in your marketing materials without technically lying.
BCH at 32 MB blocks can handle 108 Tx/s. It would only need to grow to 6 GB blocks to handle the 20k Tx/s that VISA claims they can handle. It would only need to grow to 600 MB blocks to handle the 2k Tx/s that VISA handles on average.
600MB every 10 minutes is no sweat for even modest internet connections nowadays.
With technology like weak blocks and the lighting network and other side-chains the network can handle it no problem.
This is pretty offtopic, but the amount of time it takes to download the block isn't the only factor, amount of time to process & verify the block is pretty important as well as the storage costs etc.
That's all pretty moot at the moment as BCH is averaging ~50kb blocks.
More seriously, if the name of the game is efficiency then a distributed ledger isn't the answer.