There's something to be said about being able to manage successful open source projects with lots of contributors. That's a huge plus in my book. The majority of programmers, though, are not going to be working on projects like this. A smaller plus is when you contribute to a large, quality project, because it shows you can learn to understand a new codebase and determination to get your patch in.
I think there is some value in LinkedIn integrating with GitHub, but why not just more robust links? What's the value in showing recent checkins, when I can just click through to GitHub and see EVERYTHING?
It's easy to blame LinkedIn here, but this was likely a mutually beneficial outcome agreed on by both GitHub and LinkedIn. LinkedIn didn't want to maintain the APIs GitHub uses; GitHub doesn't want to have to update its app.
LinkedIn has been trying to make forays with their jobs program, but there is only so much value that can be derived by looking at a prospect's LinkedIn profile. Previous experience - sure, but verified and authentic? Recommendations - Umm to flowery?