Lightbulb comes on.
Even assuming that Libra wasn't created as a way for FB to track your spendings even better than it is now <sorry, got to take a break due to bouts of laughter> another major reason is right there in their statement: "This means that for any unit of Libra to exist, there must be the equivalent value in its reserve"
Who can you purchase Libra from (at least originally)? FB. Who gets to hold all that money in "reserve"? FB. Who will make sure that the conditions for converting Libra back to other currencies are nigh-impossible to fulfil? FB. And who gets to collect the interest from all that moolah? Yep.
Biting the hand that feeds IT
