Conqueror is way better in teamfights because it's target agnostic, it makes dealing with tanks way easier as a melee carry much easier since true damage cannot be blocked by resistances. Press The Attack requires a focus on a singular champion, something that can often be negated to be stacked on a target that often ends up being a tank due to "Hit Tanks" phase of teamfights when they initially breakout, especially as skirmishers or ADCs.
Not to mention you're kind of blindly comparing the fact that PTA has a cooldown before it can be triggered on another target. Conqueror can be refreshed by most bruisers.
Plus add the fact that most Plat+ Bruisers are taking Conqueror, and it's even bled into ADCs who aren't supposed to be taking Conqueror with ADCs like Draven taking this keystone.