If continental crust existed above the massive oceans, it was probably hardened lava still warm from the convective overturning process. Life forms could not have survived long under such intense irradiation. The early atmosphere is likewise inhospitable. Carbon dioxide is decreasing due to its dissolution in rain and consequent transport to the oceans which store rather than recycle carbon. There is no oxygen present.
Volcanoes pump massive quantities of gases, dust and ash into the atmosphere.
Giant electrical thunderstorms are commonplace. Life as we know it could not have evolved under these conditions. The oceans provide a more protected environment. Liquid water acts as a UV shield, protecting potential organisms from UV irradiation. The stage is set for life to appear in the oceans.