I agree that pure credit networks left with no supervision have been quite bad historically, but it also appear in our new online world as one of the less cumbersome way to move value at scale. What changed since then I think is the amount of information we have on each actor of the credit network which may lead to other outcomes at scale. Also sub part of the network may be quite safe, as an example the subnet that allows BTC wallet users to pay on Stripe merchants with one hop through gdax or any other exchange.