Some reasonable questions, but I wish she focused on a different aspect.

The US dollar is still the currency of world banking, something from which the US derives enormous (and possibly unreasonable) world power. If the Libra can supplant the Dollar, that gives a small group of companies (Uber, Facebook, etc) all the financial control and influence that is now enjoyed by the US government. That's a long way off, but if anyone can do it, it's those companies.

People make the comment that the US reserve is not democratically elected, but it still acts as an arm of the US government. If Facebook controls Libra and decides it doesn't like US tax policy, it can just become a Singapore corporation and report its earnings in Libra. The 'regulatory oversight' they're inviting will likely be lobbied against in the future and become the window dressing of legitimacy, as it has in surveillance, privacy, etc.

The main point I 'think' she's trying to make about democratically elected - you can always vote in a new administration with a new approach to monetary policy. If you don't like Zuckerberg or Uber or whatever, you can scream into the void.