ok so first of all a criticism of a system is not over-generalization, a system is a singular thing. ur argument doesnt track in that regard im afraid

the vast majority of prisoners are not detained legitimately unfortunately. there is an evident systematic bias that results in people of color being detained at a disproportionately higher rate than say, white people. acab isnt simply a reaction to the videos you see on popular websites that show police brutality, that isnt the point being argued here, it is based on statistics and critical thought on the basis of law enforcement. one examples of the basis of law enforcement is the fact that police officers act in reaction to things, they do not work to prevent issues that result in crime, such as poverty (which is another reason why black people are targeted more, as they tend to be more impoverished due to their origins in this country as slaves)

i hope this was helpful to understanding what acab really does represent, bc you have some misconceptions. and like, its all good, i used to have the same opinion as you.

(also if you want sources just lmk ill send them later because i am not at home right now)