I'm so old that the last time I wrote a research paper, it was on a word processor with no Internet connection or spell check.
Given such constraints, I can't fathom the concept of waiting until the end to add all the references. If I didn't do it as I went, I'd have surely died.
I should add that we always read each other's papers before submission to get a second set of eyes for errors, misspellings, and grammatical quagmires. It was mutually beneficial as the reviewing made us all better. Is that still a common practice?