That statement implies that if you had good managers, you wouldn't have the problem, because good managers would solve the problem. That is the wrong approach to the statement. Rather, if you had good managers, you wouldn't have the problem, because good managers would ask the right questions before the problem even developed.
These workflows aren't designed for when you have a good manager, a manager who pushes testing, who demands good releases, who demands releases every day, or who demands changes to be made immediately.
These workflows are designed for bad managers (I use the term reluctantly). Bad managers are not knowledgeable, or they are exclusively focused on the short-term benefits of business decisions, without taking to account the medium-term consequences of the same decisions. This goes back to the idea of pollution, where the manager says "Just ship it now, and we will deal with the pollution later". With start-ups, sometimes managers will even say, "Push it out or we won't have a company".
The risk workflow, and the whole idea of making people accountable is exactly because of these kinds of situations, where poor decisions by management can cause huge problems.
We want to empower developers, the technical guys who are writing code and have a very good grasp of reality and potential side effects. They are the ones who should make technical decisions, because they are the ones who spend their time coding, and they understand what is going on.