I think you are right and I'm combining one thing said by Zuckerberg and another mentioned here by Graham

http://www.paulgraham.com/hiring.html

"Or more precisely, I think few realize the huge spread in the value of 20 year olds. Some, it's true, are not very capable. But others are more capable than all but a handful of 30 year olds."

So I am wrong

edit: I found where I am attributing Graham from. I am still wrong, but here is the context:

"Venture capitalists have a notorious bias against older founders—“older” being relative in youth-obsessed Silicon Valley. “The cutoff in investors’ heads is 32,” Y Combinator co-founder Paul Graham (now 53) told the New York Times in 2013. “After 32, they start to be a little skeptical.”

https://www.nytimes.com/2013/05/05/magazine/y-combinator-sil...