It appears that you are right, Linkedin appears as though it's a scam for job hunters. I was thinking to myself....
1. Yes Linkedin is a site for networking and seemingly to 'find' jobs. People get connected.
2. However, if Jack approached Jill who is a complete stranger, what would make Jill want to introduce Jack to the hiring manager.
Maybe others would like to share any positive experiences or even stories about Linkedin in.... I don't know.