Libra is what we call a “closed-loop” system. You can only spend it on things available for sale through Facebook and its associated apps. If you want to buy something through another platform, you must convert your Libra back into another currency. If it were Amazon that had created this currency, we might not regard this as a major problem. But Facebook is not (yet) a sales platform on the scale of Amazon. Yes, it promotes ads, and businesses have marketing pages. But it has a long way to go to match Amazon or Alibaba for sheer ubiquity. Although Facebook seems to be hoping that lots of new entrants will use Libra’s scripting language to design smart contracts for goods and services to be sold through its platform, the fact that Facebook is so far behind Amazon and Alibaba as a sales platform seriously diminishes Libra’s usefulness.
https://blog.kucoin.com/what-is-the-goal-of-facebooks-libra-coin-sk-st