I'm of the opinion that argument values should never be modified by their methods, because that would result in what I've been calling "backflow" or premature s

I'm of the opinion that argument values should never be modified by their methods, because that would result in what I've been calling "backflow" or premature state propagation backwards up the call stack. I think this not only hurts concurrency but also reasoning about the code and its flow. I think any new state should be via a return value of the method and not via its arguments.