It can be hard enough to get honest feedback from your friends, throw in legal liability and there's very little incentive for a potential employer to tell you exactly why they didn't hire you.
Getting _real_ feedback on anything you're doing is probably one of the most valuable inputs you can get. Depending on the context, such as applying for jobs, it can be really hard to get. At my last company I gave a few applicants real feedback on their resumes _if_ they asked for it (very few do). As much as you want to tell a person who doesn't work for you but can still sue you how they can improve, it can be hard to justify the risk.
Getting _real_ feedback on anything you're doing is probably one of the most valuable inputs you can get. Depending on the context, such as applying for jobs, it can be really hard to get. At my last company I gave a few applicants real feedback on their resumes _if_ they asked for it (very few do). As much as you want to tell a person who doesn't work for you but can still sue you how they can improve, it can be hard to justify the risk.