Taekwondoist here. I'm letting my mind wander over to arts that focus more on the fists than on the feet. From the outside looking in, it looks like boxing is the most restrictive and Muay Thai is the least restrictive, with kickboxing in the middle. (This is because Boxing is restricted to hands, kickboxing to hands and feet, and muay thai lets you clinch, use knees and elbows). From the perspective of someone building up their martial arts skills, what does someone get out of choosing to go with boxing over the more open sports of kickboxing or muay thai? Or is it simply that you get to focus more on punching?