Clean code does not prevent writing bad code, it just makes it a bit easier to write good code.
OF COURSE you can follow the principles and still write bad code, because so much more goes into it, including skill.
A giant method with everything laid out, potentially mixing abstractions sounds like a nightmare to me. It leads to cognitive overload.
I never claimed it's not important, I'm just saying it's not relevant here, as there is no context to where this method was put in the code.
As I said, it might be top-level. You have to mutate state somewhere, because that's what applications ultimately do. You just don't want state mutations everywhere, because that makes bad code.