Coacervates probably provided a nitid separation between an internal and an external environment and thus the organic material within was not lost to the ocean. The enzymatic action inside that internal environment could develop in different manners increasing the speed of specific chemical reactions.
Coacervates also allowed the molecular flux across its membrane to be selective. Since containing different molecules and differently organized from each other, coacervates could have promoted a competition for  molecules from the environment setting out an evolutionary selection.