I'm not sure many people would be keen on deploying their entire cloud on Facebook either. Forget about privacy concerns and all that, it just doesn't make sense when they have the 'move fast and break things' philosophy.
The last thing you want in high availability cloud infra is a team of engineers who will sacrifice stability for innovation.
Even if they did do it, there's not a chance they could launch it under 'Facebook'.
Do they have a "move fast and break things" philosophy in 2020? I know they did a decade ago, but is that still true today? Further, does that philosophy apply to their core infrastructure, or just leaf-node feature development? Is there any indication that Facebook's cloud infra team sacrifices stability for innovation? When was the last time Facebook had a major outage that was traced to some core service? How does their infra track record stack up to AWS (I'm a happy AWS customer, but their infrastructure flakes on us in a major way several times per year)?
The last thing you want in high availability cloud infra is a team of engineers who will sacrifice stability for innovation.
Even if they did do it, there's not a chance they could launch it under 'Facebook'.