What you say is true, but it's only part of the truth.

The other part is that some individual cops really are a lot worse than others: https://www.ft.com/content/141182fc-7727-4af8-a555-5418fa46d09e

So individuality still matters. All the factors you state are true, but they're not everything. We need to address both group psychology and individual psychology. (And how group psychology and individual psychology interplay to allow groups to tolerate that kind of individual behavior.)

In particular, when you can identify the worst 20% of offenders and potentially fix 50% of the problem, leaving that kind of gain on the table is just plain foolish.