I do not think that "most system use phased arrays". Phased arrays have several system advantages over a parabolic dish:
1. The phased array comprises a n umber of small radiators which have to be fed in defined phase against each other. Earlier such number was costly to make and adjust, now it is easier.
2. Due to a high number of radiators, some can fail or be destroyed in combat, still the antenna can operate.
3. As the phase control of individual radiators is digitally controlled, antenna pattern direction and shape can be controlled, too. This is a system advantage, and the does not need to move to change direction, or only slowly while the beam moves rapidly. Multiple beAms can be generated.
On the other hand, parabolic antenna with a simple radiator is lower cost if no fast scanning is needed.