In my view Google does a lot of analogous "rehostings" -- they just have a lot more lawyers and lobbyists to get away with it. Consider some of the places they tried and failed at this: the Google Images/Getty settlement; the YouTube/RIAA settlement; the fines and shutdowns of Google News snippets in multiple countries. Any one of these failures could plausibly destroy a smaller startup, or even send a person to prison. (I mean, Google News snippets -- isn't that just "deliberate copyright infringement on a massive scale", if you squint?)
They're qualitatively not all that different from SciHub.
> Google News snippets -- isn't that just "deliberate copyright infringement on a massive scale", if you squint
News snippets seem analogous to thumbnails in image search.
I imagine a fair use defense might be affected by 1) how much of the content is used (e.g. small abstracts vs. full articles) 2) whether the use is transformative (e.g. for an internet search index vs. in a virtual newspaper), and 3) whether the use is commercial (e.g. whether it's by Google or archive.org, and whether there are advertisements shown next to the snippets.)
Well, sure! This boundary between what is and isn't legitimate in copyright law is a nebulous, culturally relative thing. That's the point I tried to make, by analogizing Google's legal problems with SciHub's.
I agree that Google News snippet things are exactly what US "fair use" exemptions were written for, and are clearly a net public benefit. Some people don't; French law for instance definitively falls on the "deliberate infringement on a massive scale" side,
Thesis: mainstream thinking overstates the moral difference between these two -- and understates the morality-distorting effect of money, lawyers, and lobbying.
They're qualitatively not all that different from SciHub.