LOL that's how you create Evil in this world. Evil that grows exponentially under favourable circumstances.
You don't have perfect information, and neither does the audience watching your actions.
Consequently, you will cock it up and harm an innocent sooner or later. Or the audience will cock it up and wrongly assume that you did.
Both of these lead to uncontrolled escalation under unfavourable circumstances, and "mowing the grass" under favourable circumstances.
Due process is a set of tools for mitigating these problems. Its implementation is necessarily human and imperfect, but all societies that have tried to do without it have self-destructed, either directly or by making too many enemies.