> why do you allow managers to say how to develop software when you are hired to be an expert on that matter?
Because at most companies, you have a simple choice: follow the prescribed procedures, or work somewhere else. I have absolutely quit jobs that were too egregious, but that doesn't change the situation at that company.
Maybe losing valuable people is not affecting company straight away, but it surely affect the project. And with few project failing miserably (as they will if you do corporate waterfall) something might change. If not, then the whole company might fail. Remember, companies compete with each other, it just takes more time for some to fail.
Because at most companies, you have a simple choice: follow the prescribed procedures, or work somewhere else. I have absolutely quit jobs that were too egregious, but that doesn't change the situation at that company.