What makes you think companies are restricted to doing one or the other? They can be doing both.
The real question is what they do with the feedback (whether it's from an exit interview, or during yearly reviews, etc).
The real question is what they do with the feedback (whether it's from an exit interview, or during yearly reviews, etc).
The fact a person feels the need to "vent" at their exit interview shows that the company has not been seeking that kind of feedback during the employment duration.