HOW COME EACC doesn't have prosecutorial powers?
It is both good and bad. Depends on your point of view.
There is nothing stopping the DPP from donating his powers to the EACC or any other entity. He usually donates the same to private lawyers to prosecute matters in which he would seem to be prejudiced.
State Counsels all over the country take prosecutorial decisions.
The Immigration department has been operating parallel to the police, taking prosecutorial decisions and presenting suspects in court without the input of the DPP.
Corruption is just cash. Even sweepers get some. Who would give up that?