Earlier quoted context omitted.
I see it as Peter saying hire for culture, Mark saying hire for talent.
That's how I took it as well. I remember reading from Max Levchin (?) that a company should hire people exactly like them, culturally, early on. This helps reduce unnecessary conflict when the only thing you're focused on is growth. A prime example is why early startup employees come from the same school as the founders. I think later on, bigger companies focus on talent and culture equally (for the most part).
I haven't seen stats on startup hiring, but I read this about investment, which in my opinion stands a good chance of having a similar effect:
http://hbswk.hbs.edu/item/7069.html
"The probability of a successful exit outcome decreases by 18 percent if two venture capitalists who previously worked at the same company partner up in the syndication.
The likelihood of success drops by 22 percent if co-investors attended the same undergraduate school.
The negative effect of shared affinity is even stronger when it relates to ethnicity: Collaborating with someone from the same ethnic minority group comes at the expense of a 25 percent reduction in performance."