The reality is all prosecutors must successfully prosecute in order to stay in office. Corrupt leftist prosecutors are letting real criminals run free and using the power of their office to prosecute their political enemies.
There is however an inherent weakness in this corrupt system and that is the jury. All cases brought by these criminal DAs could be forced to a jury trial. It only takes ONE juror to derail the case. If the people decide they've had enough it would be pretty easy for them to decide that no prosecution by a corrupt DA will ever be successful. This would effectively nullify the DA and any case they bring.