Their greed is matched only by their arrogance. I would not be surprised to see the end result of this process being a truly serious anti-trust effort against Facebook itself.
I do think Mark Carney makes some good points about the benefits of and reasons for moving from the USD to a bancor-like digital and/or crypto reserve currency for common use, but (for the reasons you mention) that’s not happening without the direct involvement of the US Fed and other major Western central banks. I don’t know if Zuckerberg saw Libra as stealing a march on them from the private sector or not, but the US government was bound to react as if it was.