Being old enough to have gotten through college writing papers on pen and paper, you can still do some editing along the way. Use index cards, as an example - you write an outline in a notebook, you write out sentences and paragraphs for each point on an index card, and then you can shuffle the cards around until you nail down the order in which you want to present the content. Once you have it down, you re-write it all onto paper. And often, then mark up your draft and re-write it again with corrections.
I would never go back to that process, of course. It was painful then, and would feel even worse now. But it was possible.
Not the OC, but for me what I lost was the identification of a set of clear, discrete points (with references) that I initially thought contributed to the essay/document.
Sometimes I discarded the nuggets as better ones came along. Sometimes the thesis subtly changed as I gathered these nuggets. Sometimes the layout changed drastically as I shuffled my index cards. All before I even committed to my essay structure.
Not OP, but having some similar experience I'd say being more grueling, it forced the writer to accumulate experience faster. I'd add that besides the management of the aforementioned snippets that could be copied in at same point, part of the snippet-level editing, that nowadays goes on the computer, before it was just done mentally.
I would never go back to that process, of course. It was painful then, and would feel even worse now. But it was possible.