Just to be the contrarian: my first job in my current industry was through a recruiter on LinkedIn. It got me an instant 50% salary bump and after a few years and promotions I was making double the previous job.
My second job was... through a recruiter on LinkedIn. It got me an instant 30% salary bump and now after more years and promotions I'm over double the first job.
This in in a country where I had immigrated 10 years prior. For me linkedin is the best social network ever.