"I think the question we have to always ask is: how many people should we be training? My intuition is you want the gates to be very tight. One of my friends is a professor in the Stanford Economics department. The way he describes it to me is that they have about 30 graduate students starting PhDs in economics at Stanford every year. It's 6-8 years to get a PhD. At the end of the first year, the faculty has an implicit ranking of the students, where they sort of agree who the top 3-4 are. The ranking never changes. The top 3-4 are able to get a good position in academia. The others not so much. We're pretending to be kind to people when we're actually being cruel.
...It's the supply and demand of labor - if there are going to be good positions in academia where you can have a reasonable life, it's not a monastic vow of poverty that you're taking to be an academic... if you're going to have that, you don't want this sort of Malthusian struggle. You have 10 graduate students in a chemistry lab, where you have to have a fist fight for a Bunsen burner or a beaker, and if somebody says one politically incorrect thing, you can happily throw them off of the overcrowded bus. The bus is still overcrowded with 9 people on it. That's what's unhealthy."