> These would be just as traceable in your IDE/debugger.
A debugger can trace a single execution of your program at runtime. It can't statically verify properties of your program.
If you pass state to your functions explicitly instead of looking it up implicitly, even in dynamically typed languages there are linters that can tell you that you've forgot to set some state (and in statically typed languages, it wouldn't even compile).
A few posts up I clearly said use encapsulation and then mutate state via known methods. These would be just as traceable in your IDE/debugger.
Further, I have also repeatedly mentioned both module-level and thread-level "globals".
And I understand how concurrency works.
Take care.