
This can be really good as companies don’t like the liability of having user data in the first place. This can be bad, however, if the user is “misbehaving”. There’s no way to kick out the user that’s spamming your blockchain with frivolous data or has figured out a way to profit in some fashion that causes other users lots of inconvenience. This is related to the above observation that incentive structures have to be designed really, really well in that a user that figures out an exploit is not likely to give that up, especially if there’s profit for the user.
The main thing distinguishing a blockchain from a normal database is that there are specific rules about how to put data into the database. That is, it cannot conflict with some other data that’s already in the database (consistent), it’s append-only (immutable), and the data itself is locked to an owner (ownable), it’s replicable and available. Finally, everyone agrees on what the state of the things in the database are (canonical) without a central party (decentralized).