Now this is usually in my opinion not a good advice (it is like reintroduction of global variables) as unnecessary state certainly makes things more difficult to reason about.

I have read the book (not very recently) and I do not recall this but perhaps I am just immune to such advice.

I like his book about refactoring more than Clean Code but it introduced me to some good principles like SOLID (a good mnemonic), so I found it somewhat useful.