> So for example Amazon could easily implement this, and do it at scale. Would you trust Amazon? To both keep custody of your data, ensure that it will always be available, that it would not be meddled with? Would an enterprise like Wal-Mart trust that?

Yes, far more so because Amazon will give you a legally binding contract with things like SLAs.

The problem with decentralized systems is that serious apps cost more to run but people generally don’t want to pay for things which don’t benefit them. You can ameliorate the performance and reliability problems of a blockchain by throwing capacity at it but there’s always the question of why you wouldn’t spend less to run your own private system to avoid the possibility of having problems caused by people you don’t even know about.