Yes, there is a huge benefit for someone like me who has worked in many different cities. It allows me to keep in touch with people I've worked with and see where they get new positions. The key here is that it's a tool: it's only as valuable as what you put into it.

It has essentially replaced the Rolodex people used to use years ago.

If you aren't open to recruiters reaching out to you, you can make that plain and clear in your summary... "I don't speak with recruiters" or "Not looking for a position."