Actually it depends. Doesn't mean RCBO is better.
From the developer diagram, the MCB+ELCB (10mA) (i think is RCCB) is already following Suruhanjaya Tenaga guidelines and provided protection for overload + leakage current.
Use RCBO if only MCB is provided, then people replace the MCB with RCBO to provide 2in1 protection where there is no RCCB connected.