He talks about working for a company after finishing college to learn about how they operate and do business. You know what I learned in the five years after college I worked for a company as a dev? A whole lot about software development. Nothing about hiring (beyond what I gleaned while interviewing), basics of management and nothing about marketing or sales. You know what I learned in the first few months of trying and failing to launch a business? A heck of a lot about everything, including a lot more about software development.
Working in my trade for a few years out of school made me very good at what I do but it certainly did not make me a very good entrepreneur.