Having ducted AC that brings fresh air to each room has the obvious drawback that you're wasting energy to cool down (or heat up) rooms that do not contain any humans. Like when you are sleeping in your bedroom, there's no point in cooling your living room and kitchen as well in most cases. A split system that only circulates air within one room would use a fraction of the energy in that case.

Anyway, you could always install one of these in addition to your aircon if you want air from the outside: https://broan-nutone.com/en-us/fresh-air-systems/residential