[22122]

i think the answer is the unlikelihood of having life get started in the first place, we have a better idea of how life evolves than how it began. i think the reason it happened so early on earth's history isn't because it is common, but because something about the conditions of the early earth was uniquely well suited for it to happen

[bediger4000]

Starting so rapidly after there was water on Earth's surface, and probably starting on Mars very rapidly as well, mitigates against this view.