Where I work, we put a lot of effort into giving honest, actionable feedback to anyone we interview or phone screen. (We don't do it if we choose not to phone screen someone, though.)
We tell you why we didn't proceed and what we think you could do to make a difference if you choose to try again in a few years.
This is for our own benefit as much as the job seeker's. We don't want to leave a sour or even neutral taste in someone's mouth just because it didn't work out. Someone who is a bad fit now might be a good fit in the future, as they change or as we change, or we might be wrong that they are a bad fit now.