Facebook hires tons of zero passion 10am-4pm engineers. It might not be deliberate slacking but it’s definitely not hard working.
Facebook makes you demonstrate your impact to the company twice a year. You would be hard pressed to be a slacker long term there.
The work does appear different because at that scale you spend a lot of time tracing out what's there, figuring out context, and trying to figure out how to make a change without bringing down everything else. If you're used to a small company or a small codebase where you spend most of your time writing new code it seems less productive, but it's mostly just different.
The quote is from “Howl” by Allen Ginsburg, a poem about burnout (among other things). That’s applicable to a report of people working a 9-9-6 schedule, a recipe for burnout.
Rather than being the centerpiece of intellectual activity as you put it, it would seem the vast majority of the "best minds" are employed in the field. Rather than more necessary pursuits, more people are applied to making us click advertisements and applied to the surveillance of our browsing habits and other activities. It's not just the FAANG companies. The city I live in is flooded with small ad-tech startups who are going to "revolutionize the world". On top of that, to hear the ad-tech teams are probably the only teams at FB that are working a crazy schedule speaks loudly. Very loudly.