This one is kinda tricky. A lot of people in my field get their jobs through recruiters.
Sometimes, they leave you a message on linkedin, and then it is clear that they reach you there.
Other times, they call you and you have really no idea if they found you on linked in or dug your info up somewhere else, but most likely,, they found you on linkedin.
I am not much found of linkedin, but the way things are with IT jobs, at least here, I don't really have a choice, I need to be there.
I am only ever active on linkedin when I need to look for a new job (something that has been a tad too often the last years)
But yes, I started in a new job two months ago, recruiter contacted me about it via linkedin.
I had, however just seen an ad for it, and was about to contact the company, when the recruiter wrote me. But I had already seen the job ad and was going to contact them directly, but the recruiter was too fast.
But yah, LinkedIn dominates totally...