[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.

[SideQuark]

That's fine. You also miss all papers not on arxiv. You miss published versions of even the papers on Arxiv (which are often improved versions), and you miss any benefit peer review has on those papers.

I use arxiv nearly every day, and also a few places that get things not on arxiv because the majority of papers are simply not there. Arxiv is paid for by universities paying subscriptions, locked in for five years at a time. It's also funded by Simons Foundation (which may not pay forever) and Cornell and many individual donors. Affiliate groups like professional societies and govts pay huge sums to keep it running. Many companies pay 10's of thousands annually to be members.

Piggybacking on their money while taking affront at a bigger, more comprehensive service, because they dare post an ad, seems somewhat short sighted, but to each his own.

ResearchGate is the largest academic social network, so many use it for that reason. Here's an (2014) Nature article on researcher usage of various sites that may surprise you https://www.nature.com/news/online-collaboration-scientists-...

Since a significant number of job postings for researchers as well and communication and networking opportunities are widely used on Research Gate, none of which is present on Arxiv, you are simply missing likely useful contacts and tools for your career. And I write this as a researcher for several decades, long before any of these were live.

As I said, enough people find value at research gate that millions do pay.