Prosecutorial over-reach is a byproduct of the particular structure of our adversarial system and current views on the role of our legal system. This was not one rogue individual, it was the execution of an institutional mindset that has given us the highest incarceration rate in the world.
Pinning all that on one person allows something to be done without causing change.
They have no impetus to change until there's enough anger to make them afraid.