Kata (traditional forms) are just movements of the human body. They are muscle-memory building tools used to get your body coordinated and at the same time learn movements that can be applied in a combative situation. Just like a boxer shadowboxes as a means to practice alone, a karate person practices kata. The only difference is what happens afterwards: training to apply it.
We agree that 99.9% of karate schools don’t go beyond just learning the forms. But with the right method of practicing and pressure testing the movements, karate can work. This video provides examples of similar movements found in Okinawan Karate, an art that’s hundreds of years old, and modern MMA.