What is the rationale of having maximum coarse aggregate size in a concrete mix design form?

Larger aggregate size reduced total surface area of aggregate leading to lower water demand.

Larger aggregate size reduced cement requirement.

Required cover and available spacing of  reinforcement should also be considered for deciding maximum aggregate size.

Unproportional aggregate size will result in segregation of concrete mix or will not produce cohesive mix.

same work-ability and same aggregate weight, mechanical properties of concrete are greater,,,,,,,,,,,,,,

for given workability , application of concrete and mode of placing the concrete and rebar congestion..etc. Increasing the size of aggreagtes will decrease cement or cementious content.

for same workability and same aggregate weight, increasing the maximum size of  aggregates lead to decrease the water demand of the mix and the water/cement ratio and the mechanical properties of concrete are greater