OK, so according to him there's code review and some automated tests.

But that still doesn't address wide open access to the live DB by brand-new devs, and the complete disregard for having a dedicated QA team.

Why QA? I would think FB engineers are more busy doing real work at work than fooling around on their own site (heh, the irony) and finding out that Junior Dev 39's change to the thingamabob broke chat for the umpteenth time in IE7. And as many people have pointed out here, they are a platform for many other businesses now--there's no dogfooding that--and the API stinks in terms of stability and documentation.