Are you making the distinction that the process occurred experimentally in "droplets of pure water"? First of all, by any definition the water in Miller-type experiments is not pure: it contains a mixture of gases. Second, peptides could never form in pure water for the same reason; pure water does not contain the elements necessary to construct amino acids. So the "in pure water" phrase is a bit of mumbo jumbo some creative writer at scitechdaily probably threw in there, not relevant to the quote, imho. I doubt it appears in an original publication on this work.

I have read (many years ago), that although amino acids form readily enough from ammonia and methane as precursors; getting more complex molecules was ever more hit-and-miss in these types of experiments. Partly this was thought to be due to the relatively small quantities of amino acids in the apparatus from the first-stage syntheses. So some modified experiments began with added amino acids to simulate hypothesized concentration effects, and/or adding clay or other substrate that might act to catalyze formation of more complex molecules. I do not have access to journal libraries, so I can't find better than https://pubmed.ncbi.nlm.nih.gov/26508401/ (which does not mention peptide formation).