I am not asking why RNA primer needs to be added, but rather why RNA nucleotides are added as a primer by Primase and replaced by DNA polymerase I? It seems very inefficient to first insert RNA nucleotides and then add DNA nucleotides when you could have evolved to just add DNA nucleotides directly, without having to add RNA nucleotides.
Perhaps, it is an evolutionary remnant? Proof that DNA arised RNA? What do you guys think?