> A PhD applicant who wants to get a good academic job should have ~10 papers
> A tenure case should have ~40 papers
That alone would push me away from a PhD in CS. In economics, it's closer to what he said was the case when he was new:
> I got tenure from Berkeley in 1976 — With about 5 papers
1) it gives advisors a lot of influence over the student's career (obviously, if you have an actively hostile advisor things will be hard in any system, but I have known successful faculty who had indifferent fund-and-forget-style advisors who wouldn't know enough about the student's field to write a good recommendation)
2) informal "I like this person, hire them" networks tend to select for people who are like current participants in the network
I agree that a coarse "do they have at least x papers?" way of evaluating researchers is silly. But it's not crazy to have 10 papers when you graduate. That's about one paper every 6 months in a 5-year program. Six months is a long time, almost a thousand hours of work. If three people are focused on a project, it's pretty plausible to get a cool result in six months.
Personally, if I saw someone published a ton of papers during their PhD, I'd question the quality and importance of their research. Quality tends to decrease with quantity in my experience. And it appears too easy to fake importance. In my field I watch out for vague words like "novel" and "fundamental" in paper titles as evidence that the work is probably overhyped. I'm fairly well read in my field and I can sense the disappointment in people when I tell them that their "great" idea was done before, particularly when it was done better and/or a long time ago. (I take no pleasure in doing this. I just wish people spent less time reinventing the wheel.)
I think I could have had 10 papers during my PhD if I focused on easily-published things and "salami-sliced" my papers. But I focused on what I thought was more important and made the scope of each paper larger than normal because it saves readers time.
Proxies that are characteristics of the researcher might be better (or at least should be considered), like the willingness of the researcher to put "skin in the game" so-to-speak. I'd have a lot more confidence in research conducted part-time by someone on their own money than someone using another person's money (which has much less risk). Taleb has written about this as I recall.