Sometimes it seems that contacting the employer directly would be a better way to find a job than working through a recruiter. While that seems to make sense, using a recruiter can be beneficial because the recruiter communicates with the employer and the candidate who might share a concern, or a circumstance that might never be told directly to the other party. A good recruiter will listen, and try to clear up a misunderstanding and advocate for the candidate, or employer in ways not likely if there were no recruiter. Note, we do not have to be active in every step of the process and we often encourage the candidate and employer to interact directly, but even then a good recruiter will be touching base with both parties to make sure everyone is on the same page with the same goals.
Additionally, a good recruiter can get your cv to the decision maker, sometimes bypassing (at least initially) the online application process which can be a black hole from which you get no response once submitted.