The global mutable state isn't the problem, of course, it's any of your code that uses it. Minimize that code and you're done. And yes you are correct about a

The global mutable state isn't the problem, of course, it's any of your code that uses it. Minimize that code and you're done. And yes you are correct about all of the things you referred to as 'global mutable state'. They all are exactly that. They are very useful. People use software to do changes to that global mutable state, and that global mutable state is literally the only reason the software exists in the first place. It is the primary responsibility of software to manage it. And as with anything you need to care for, the less you have to manipulate it the better off everyone will be.