No, see, that's where you stray from the path. They didn't evolve "perfectly". The systems may have evolved other ways. And did, when you look at two animals. Which is perfect? The bladder lung of a Gar, or the lungs of a lungfish?
The system isn't "perfect", it just works. If it did not, it would not persist. There were many more failed models than successful ones. But we don't see those, because they failed.
Replication is not really a mystery at all. A hydrocarbon splits, the two pieces map a version of the missing piece onto itself from available materials, and you have replication. Very easy to replicate in the lab (for the experts, not for me). Then, a more complex organic molecule does the same. Keep scaling it up it up with longer molecules, and you eventually get DNA replication.
You say things like the quote above... your first instinct should be to wonder if the people who have dedicated their lives to studying of this, oh just maybe, thought of that. A while ago. Then look up what they have to say.