There's a lot here. People have been writing books about this for decades.

Two things that need to be succinctly said:

1. Project Management is just another skill, like database management, security, or any one of a hundred other skills a tech team might have. PMs keep trying to take themselves out of the trenches and claim a special place. Every time they do that it is a mistake.

2. He touches on "waterfall" a few times. Physical things decompose into smaller physical things. That's why bridge-building is the way it is. Creative technical work is not a physical thing. It is infinitely decomposable. You take a job creating new tech and split it into 10 pieces, you've got the same job with just a lot more overhead. You can go on forever. Very quickly this natural tendency for decomposition leads to doomed projects.

Intuition will lead you astray in tech project management. Every time.