[howaboutnope]

Yet all living beings in earth are descendants of same cell, as far as we know. So if the above can happen once -- even if only "needs" to happen once, why would it not occur more than once, and lead to different "lines" of life, so to speak?

[yarg]

I suspect that the less evolved and less efficient replicators would not fare well against older and more robust forms - especially once those forms develop the ability to hunt and direct their food.

Basically, in an emergent adversarial environment running late to the party gets you eaten.