A lot of the "clean" stuff is completely out of date. It might have been justifiable to insert umpteen independent layers (ooh.. Data Objects -> Domain Objects -> UI objects; mapper mapper mapper!) into your software in the early 90s when everything was a monolith and there were such things as "database teams" and "business rules teams" in order to insulate those parts of the software from each other.
In the age of uServices where the boundary is the API and the context is completely self-contained, it's not just a bad idea it's an actively malignant waste of time.
I think there is a problem when we cancel ideas because of whom is telling them.
In my personal opinion he lacks experience with actual development and skill to even talk about code, let alone good development practices. He is a book author, not a developer sharing his expertise.
He spouts hot air for money.
Personally I think he has more misses than hits and everything he writes should be taken with a large grain of salt, but occasionally he hits upon some interesting ideas.