Earlier quoted context omitted.
I'm actually going to go out on a limb and defend their choice of MobileCoin. Signal has always been a decent privacy/convenience tradeoff and MobileCoin is no different. Features like phone numbers and contact uploading were always a user friendly tradeoff. They also seem to trust SGX. Monero's isn't slow by any means but isn't fast either. UI changes can alleviate the issue but being unable to spend your entire bal…
They could've created a federated SGX-based model on top of any of the existing cryptocurrencies. The only reason for them to invent a new one is making $$$.
What they've done is essentially take Monero as a base, remove mining and use Stellar Consensus then solve any new privacy issues that arise.