This post is nonsense. 1) FB claims they want to eventually make it a public network. Therefore, they'll need BFT sooner or later. 2) No blockchain can match a centralized system (WeChat, Visa, et al). 3) Very few languages have a formal semantics written in Coq. 4) So what if the crypto lib has additional functions? Algorand has VRF code in their repo. Is the whole project doomed now? And it would take a huge effort to verify a crypto lib ala Everest. Even cryptographers don't do it. 5) In the US many banks are in a consortium called Zelle which allows retail customers to send money around. It has finality; can't be reversed.

I don't give 2 shits about Libra. Gov'ts will clobber it anyway. But these criticisms are mostly "why didn't Libra do the latest bleeding edge researchy thing that no-one else does?" Because they had to ship this century, that's why.