Facebook 'looks to quietly cull 12,000 underperforming workers'-15% of its staff

If Facebook has 80K employees, what the f*ck do they all do? Are there that many sales critters and content reviewers? I would think you need to keep the critical infrastructure staff small to avoid the herding cats problem. And DevOps can't be that big as I would think it scales (make work, clone data centres). Are they having gobs of tiger teams developing products that never see the light of day? Did they hire all these people to keep them from others? Keep up appearances?

I've worked my whole life for smaller companies who managed to produce with 5-20 person dev groups and support groups of double that size. And it's not like there's significant user support for the unwashed masses from the social media titans. Pointers to summaries of how staff breaks down at these companies would be greatly appreciated!