My company does hybrid work, so it has fewer desks than employees. If you don't arrive early enough on event days you'll spend your day working on a sofa with your laptop on your legs. How productive!
It’s fair to says hers was bigger than average, and access to her meant walking directly through the desk areas of two assistants, however it was undeniably a cube without full-height walls and in the style of everyone else’s at that worksite.
Meg also had a conference room nearby reserved for her use, and did a fairly typical amount of travel (a lot!), but it wasn’t a purely symbolic gesture, the few meetings I had with her where we arrived early she often arose from her desk in the cube and walked over to the conference room. It seemed the desk got used.
At that time HP was doing around $120B a year in revenue and had 330,000 employees but she didn’t say, “I need a closed door office”.
If someone needs to hold frequent meetings or be on phone calls, there's nothing wrong with giving them a closed door office.
All that said, I don't think that's the norm even at Facebook, just a carefully maintained illusion.