Banks are heavily regulated, and Libra would not be just another cryptocurrency. It's reasonable to expect that it would have been (and still might be) considerably more powerful than any one existing bank.

Comparing it to the toy money that existing crypto currencies are is likewise entirely irrelevant. It's structurally different for one, as Facebook et.al. would back Libras exchange rate. It's also backed by enormous economic power:

https://libra.org/en-US/association/#founding_members