Water is a poor medium for condensation polymerisation. Polymers will hydrolyse in water over geological time. Heating to evaporate water tends to destroy some vital amino acids, racemise all the amino acids, and requires geologically unrealistic conditions. Besides, heating amino acids with other gunk produced by Miller experiments would destroy them. The Polymerization Problem .
Miller experiments produce five times more unifunctional molecules than bifunctional molecules.
The Polymerization Problem . Also, the alkaline conditions needed to form sugars are incompatible with acid conditions required to form polypeptides with condensing agents. A small fraction of wrong handed molecules terminates RNA replication, shortens polypeptides, and ruins enzymes. Life requires catalysts which are specific for a single type of molecule. Prebiotic polymerisation simulations yield random sequences, not functional proteins or enzymes.