The whole “unbanked” thing is really unconvincing, because there's no way Libra/Diem will be usable for people who don't have identity documents and the evidence needed for KYC/AML forms, and that excludes most unbanked people. As for international money transfers: TransferWise and the like are already providing better solutions in that space without forcing you to use Facebook Coins. Now you might say that mostly ca…
The key to this is the part of the White Paper that notes they'll need to create a digital identity standard. This is something that's been widely advocated. But imagine a private company creating one, particularly one with Facebook's track record. Imagine having to use Facebook to access any money - not just Diem Dollars. (my book on Facebook's Libra/Diem plan goes into this, particularly ch 8 on privacy)
I don't think this can happen in practice. For any such system to work at all, the vast majority of the entire society needs to be using it and be satisfied with it, and then there'll always be cash anyway for which there can't be access control enforced by any one entity.