My backwards employers hired less qualified employees, and when I asked how I could improve myself, I was told "just keep doing what you're doing."

I have been dedicated to my job in the hopes of being promoted. Unlike most other employees, I am always picking up shifts, maintaining positive patron relations, always finding out answers to my questions or scenarios I would not be sure how to deal with if I became a supervisor. Basically I was highly qualified. So I didn't get the promotion. It's not a big deal, there are a lot of qualified people, so I can understand why they can only pick the best of the best. My problem Reddit, is that during my obnoxiously long rejection call from my employer, he told me that he could instantly tell me how I could improve my work if I would have liked to hear, and of course I said yes. His next reply "actually just keep doing what you are doing. You have a great personality, you follow policy, and you have great customer service."

Reddit, I want to shoot my employers. How did you guys that experienced this get by? I am just so angry