I think it does harm you not to have a profile, but only indirectly. Employers will search for you. Having no profile means you're missing out on an opportunity to make an impression before the interview - candidates with posts about things they find interesting in job-related fields, or status updates that make them look like sociable, interesting people, will benefit from that. Having no profile puts you behind those people.

Mind you, having a bad profile will get you rejected, so no profile might be better in some people's cases.