> He also rails against private state specifically. I assume again that he means private mutable state. This is generally a bad idea and is accepted pretty uncontroversially as a bad idea.

Here's a program that has some mutable state. Do you want that mutable state to be private or public? Do you want anybody to be able to change it, or do you want all changes to have to go through public methods?

Given that there are programs that necessarily have mutable state, why in the world would you not want that state to be private?