As others have said, USMMA and USNA have two different missions. USMMA’s is to produce mariners and USNA is to produce officers for the Navy and USMC. One big difference between the two is when training occurs. At USMMA, you are qualified to work on active vessels upon graduation. That necessitates majors that teach you shipboard skills (i.e. majors that lead to 3rd Mate or 3rd A/E licenses). At USNA, you attend follow-on training after graduation. It was 3.5 years after graduation before my first deployment.
Also, the Merchant Marine is very specialized. While the different branches have their distinct missions, the branches have a lot of capabilities and that requires a lot of different majors to accomplish them. The military has many jobs from engineer to accountants, and everything in between.
If you love the sea, you can’t go wrong with Kings Point. If you have a military itch down the line, it is an easy transition. Also, being a grad of KP doesn’t hold you back in any way. KP grads become doctors, lawyers, business executives, etc.