I've said this here before, but based on having dinner with him probably ten years ago now, the arXiv replaced the system that existed in the early 90's where p

I've said this here before, but based on having dinner with him probably ten years ago now, the arXiv replaced the system that existed in the early 90's where people at top research universities would mail preprints to each other, as publishing was slow and waiting for preprints to be published would put you behind the curve by quite a long time. Obviously this was inefficient and somewhat exclusive (if you weren't at a university in the preprint exchange club, you'd be hopelessly behind in your field).