The first thing a hiring manager does when they want to fill a position is look within within the company. Where's the second place they look?

They look within their network. They're going to reach out to people they personally know professionally and personally and say, "Whom do you know that may be a good fit for this job?” 

And only after that does the hiring manager then typically go to the public, which means posting the job online or publicly advertising the job. Most hiring managers would strongly prefer that they are able to find somebody that can promote or transfer within the company, or somebody in their network, before going through the process of posting a job online or making it public. 

The more you build your personal and professional network, the more people that you know will also know hiring managers.

So if you’re creating awareness, the more people you have in your network, the more likely that you are going to have people that will vouch for you with that hiring manager and say, "Yes, this person I know, [you], they'd be great fit. You should interview them."