There are a number of different ways to expand your reach in LinkedIn.
Getting your message out to more people, more people that will act upon your message.
You need a small number of relevant, tightly connected groups of LinkedIn connections.
For example, this social graph shows that I have 3 groups of connections, and some stray connections.
"I have 66 connection requests in my LinkedIn inbox that I have been ignoring because I don't know them and they did not bother to send a personal note letting me know who they are and why they want to connect.
It's so irritating.
It would be like walking up to someone at a networking event and not telling them your name or giving them your card and expecting them to take the time to figure it out for themselves.