[trextrex]

What value does it provide over linking to the original source?

Any website that constantly asks me to login is spammy in by book. It's a for profit website that adds little value other than duplicating information from primary sources and occasionally mangling pdfs with redundant information to advertise themselves.

[SideQuark]

They also provide a central place to search things, with a richer interface than Google scholar, and have centralized a significant amount of good sources.

There's a reason millions of researchers have joined. That you don't find value or know what they provide is no reason others should not learn the value they add.

[p1esk]

They also show ads: https://www.researchgate.net/marketing-solutions

As a researcher I don’t see any value there. I’ll stick with Arxiv, thanks.