Fyi... Zuckerberg didn't "retain" unilateral control. He lost his 65% majority ownership control because it was reduced (diluted) to 40% when Peter Thiel invested in 2004.[1]

What eventually happened was that Zuckerberg later consolidated voting power from other shareholders like Sean Parker and Accel Partners.[2] Why would they give voting power to Zuckerberg?!? Because Zuckerberg was doing a good job running the company.

Yes, Facebook also later set up class B shares with 10x voting power for Zuckerberg. But investors won't accommodate founders with that structure unless the company is a big success.

So in short, MZ lost 65% control, and then eventually got majority voting power back after some business events. Even though he now only owns ~14% of Facebook, an article said his voting share was still at majority of ~58%.[3]

[1] Facebook ownership was divided between Zuckerberg, with 65%, Saverin, with 30%, and Moskovitz, with 5%. After the transaction, the new company was divided between Zuckerberg, with 40%, Saverin, with 24%, Moskovitz, with 16%, and Thiel with 9%. The rest, about 20%, went to an options pool for future employees. -- from : https://www.businessinsider.com/how-mark-zuckerberg-booted-h...

[2] https://venturebeat.com/2012/02/01/zuck-power-play/

[3] https://www.bloomberg.com/news/articles/2021-05-26/facebook-...