It would still be centralized....which means they control it...which means they could alter it at any time.
Plus what is their incentive? Why would someone like Zuckerberg and his Wall Street buddies give up all the profits.
Also, I surmise that within the next couple years, decentralized is going to be part of the everyday vernacular. There are many movements that really are heading that way without knowing it....those tired of having that data sold...the anti establishment people.....the anti KYC people....those tired of all the advertising....the fake news..etc...