[fredkbloggs]

No, there is no truth to this whatever.

Having a professional network is enormously helpful but not (as of this minute) strictly necessary. LinkedIn offers a representation of that network, not the network itself. It isn't a relationship-creating tool, and whether you have an account there is not relevant to the hiring process. At the very most, it might offer you a way to contact someone you've worked with in the past who might help you get an interview. Just like email or your phone's contact list or that group of people you drink beer with on Fridays.