It's not a crypto currency in the p2p sense. It's federated, and the servers are run by the initial investors. It's world-Venmo.
1. All the interest from the reserve (which isn't all hard cash but also low risk securities) goes to the investors. No ability to create your own bank offer interest and compete.
2. Undercuts sovereignty. The HN crash may laugh but ask Yanis Varoufakis what it's like when you can't do your own monitary policy. Would you rather deal with the IMF or Facebook?
Now that is a genuine dilemma. I'd say the IMF, purely because there is enough historic data to use Bayesian inference to guide you in doing the opposite of what they advise.
Specific cryptocurrencies on the other hand, well, where do I start? We could be here all day.