You can't just spin up your own CoinBase if you don't trust coinbase.com. I mean, it's BitCoin, so you can run your own transactions, but you can't do any of the other stuff CoinBase does.
But with Stellar or something based on its consensus protocol, you can run your own node if you want, or more likely, a bunch of public nodes can exist and you can pick the one you trust to work with. For example, if banks decide to start working with MobileCoin, then Chase could offer a node and, as a Chase customer, you could decide to trust their node (since you already trust them to manage your money) and use that one.
> you can run your own node if you want, or more likely, a bunch of public nodes can exist and you can pick the one you trust to work with
Still not getting it. If I don't trust CoinBase, I can go to any other online wallet that manages my private keys. With some effort, I can even start one myself. If Chase is running such a wallet, I can use them.
How is a decentralized protocol not a superset of a "federated" one?
Every node in Ripple or Stellar works with the same global state. You have to trust Coinbase not to run away with your money, but your Stellar node cannot. The consensus system is more like a replacement for proof of work, ensuring that no one double spends.
But with Stellar or something based on its consensus protocol, you can run your own node if you want, or more likely, a bunch of public nodes can exist and you can pick the one you trust to work with. For example, if banks decide to start working with MobileCoin, then Chase could offer a node and, as a Chase customer, you could decide to trust their node (since you already trust them to manage your money) and use that one.