I think Facebook already have our personal information, supplying our kyc documents is only to double check it with our Facebook profiles.
The coin will succeed since Facebook is a trusted platform.
The coins might succeed due to popularity of facebook. Nothing else. Libra is going to be a centralized currency.
Why would we need another centralized currency system, when we already have paypal and other e-wallet currency? If we will have to provide our details and identification then what is the difference between this system and paypal? The main goal of crypto currency was to create a decentralized platform which will give us financial freedom. We won't be getting any of those features through facebook coin.
There is not going to be any difference between the coin facebook releases and paypal or any form of fiat, so from our perspective such a coin is useless but from the perspective of facebook this is great, they will create their own coin and if they force their customers that any payment for their ads needs to done in their currency then you can bet that it is going to gain huge adoption all over the world, this is just speculation but maybe facebook does not want other institutions to know how much they are earning and creating their own coin could be a way to hide their profits.