The LinkedIn profile is meant to be an extension of your resume and is therefore complementary to it. You'd include in information in that LinkedIn profile that's not in your resume but that would be of serious interest to anyone who wants to reach out to you. The LinkedIn profile is best used to get around the limitations of the resume format and attract high quality recruiter attention. I use the LinkedIn profile to not only say the things I do but to (briefly) say why I do some of the things I do.
You may have several resumes in your drawer, each of which is targeted to a position category. However, you are entitled to just one LinkedIn profile. So the LinkedIn profile is the place where you put yourself together. A five page LinkedIn profile is readable in a way that a five page resume is not. If you do the profile right, that is.