Blockchains have consensus built in at the protocol level. Sure, you could share an append only log, but who settles disputes? All that functionality has to move off chain, and that's a bigger risk, in my opinion.
> Blockchains have consensus built in at the protocol level
They have it built in based on picking the chain which the most work has gone into.
Arbitrarily assigning a number to a transaction and having everyone to agree to pick the smallest in the case of conflict is easier and works fine if your members are all trusted to not maliciously abuse that facet of the code.
Proof of work is throwing away resources to solve a problem you don't have if no one is crafting malicious transactions.
>Arbitrarily assigning a number to a transaction and having everyone to agree to pick the smallest in the case of conflict is easier and works fine if your members are all trusted to not maliciously abuse that facet of the code.
This would be like a traditional eventually consistent distributed database (using total order to resolve conflicts).
And we might ask "why did those deploying private blockchains not just use that kind of thing?".
I'm not sure, but potential reasons are:
1. That kind of thing doesn't actually exist in a form that they can easily use, so they re-purposed existing, reasonably proven blockchain technology to achieve an equivalent functionality.
2. The parties don't completely trust each other so in fact malicious transactions can be crafted.
3. They don't trust their software to not craft malicious trasnsactions and the blockchain provides a neat way to filter them out.
Proof of work is but one consensus algorithm. There is proof of stake, proof of authority, delegated proof of stake, etc. Dozens of different approaches out there different from Bitcoin.
