Earlier quoted context omitted.
What's the counterargument to this?
The incentives don't seem to align in that direction. What would be the point for Facebook to create a promote such a currency if they can't control it at some level? I fully expect that even if the core of the cryptocurrency might actually be decentralized and not directly controlled by Facebook (and I don't believe that either, for the record) the practical implementation of this will give Facebook more than enough…
Facebook has nothing to gain from decentralization when all their business depends on slurping up data? That couldn't be further from the truth. Reliance on selling personal data is a huge flaw in the business models of companies like Facebook and Google, and they're eager to diversify. Moving money around has been one of the top businesses to be in since the start of civilization, and it's an obvious target to diversify into.
Your last comment about libertarians being shortsighted is somewhat unrelated, but I have to disagree. That philosophy is all about avoiding expedient means of doing things if they have long-term consequences. Using the force of government is almost always the fastest and most effective way of accomplishing a goal, but the escalation of centralized power over time can lead to catastrophic results, and libertarian-minded people are willing to give up short-term benefits to avoid those long-term consequences. Likewise, businesses can also be short-sighted at times, but they do occasionally employ people who see that too much centralization can lead to collapse in the long-term, and the thinking behind Libra seems to reflect that mindset.