Why not just have MMA as the only fighting sport instead of boxing, kickboxing, and all of it's aspects?

I don't understand what the point is of having boxing and all this other crap. MMA is just like street fighting. If you were in a street fight would you just only use boxing or kickboxing? OF COURSE NOT! MMA has all aspects of fighting and it is true fighting. I am more impressed with an overall fighter vs. a fighter that is only good at one aspect. That is like taking out aspects of football and turning it into a sport lol it is so retarded and makes no sense.