[akvadrako]

I don't know what field you are talking about, but in physics only about 95% of papers I want to read are published on arXiv, including older ones. I assume most researchers occasionally read something from scihub or subscription services.

[tomrod]

Downside to this is if there is a major revision during publication peer review that doesn't get reflected in arxiv. Economics has has SSRN for years, and while not as widely adopted I would presume the issues between the two are similar.