I've seen the same thing happen in a large corp I've worked for directed by the advice of McKinsey.
The funny thing in this case though was that it was Accenture which advised them to hire the engineering department two years prior to help with innovation. Then after a couple of years of building out the team they advised them fire the whole department and outsource it to cut costs. The only people who remained were managers.
It is kind of nasty to think about the timing though. If true, they kept those managers around to do the very undesirable and time-consuming performance cycle (yearly review) work and will be letting them go now that the process has concluded.
Zuckerberg owns controlling interest over the company to the point where the board of directors are essentially advisory. I believe I read that he owns over 75% of Class B shares, for which he gets 10 votes for every 1 vote that a regular Class A voter gets.
That's a lot of power. This has allowed the company to ignore Wall Street in the past, which makes me think he's not suddenly concerned about Wall Street now. Whatever Zuck does is really his choice and responsibility.
Whats more interesting though is how the let go workers venture within there cultural spheres. Meta workers are more likely to go to places, that have adapted similar cultures, with AB Tests.
Then the layoffs started. In honesty, mostly OK decisions but a few really bad key ones. Then I watched the super smart people see the writing on the wall and leave, mostly to Google.
Then I felt stupid, if all the smart people left what did that make me? Well, it made me a big fish in a small pond, and I probably learned little of value over the next couple years, until I inevitably left too.
The company now is a sad shell of what it once was. I guess this type of story is all too common.