>> The current behavior is explicitly documented, so presumably
>> it can't be (easily) changed

And it isn't clear that it would be desirable to change this even if it were possible - doing structured resource clean-up seems consistent with the rest of Python.

That being said, I can see the user case for this.

If you added this as an argument to shutdown() then you'd probably also have to add it as an option to the constructors (for people using Executors as context managers). But, if you have to add it to the constructor anyway, you may as well *only* add it to the constructor.

I'll let an active maintainer weigh in on whether, on balance, they think that this functionality is worth complicating the API.