Whether you're the job applicant or the employer, you'd probably feel cheated. Imagine LinkedIn was a headhunter who charged the employer to fill a job, but also took money from an applicant to submit her resume first. That's called double-dipping.
Welcome to the "job board" model for recruitment advertising, where the middle man charges everyone and manipulates the database, and where matching qualifications to job requirements is way down on the list of concerns, right beside those poor "basic users" who didn't pay to play.
http://www.pbs.org/newshour/businessdesk/2013/08/ask-the-headhunter-is-linkedin.html