If you haven't already noticed, there are an ever-increasing number of faked profiles on Linked In. On average I get 1 a week trying to connect with me - so around 50 a year, and my network currently is less than 2000 people.
At best they are harvesting your contact information so that they can sell a list of contacts for spamming / marketing purposes. At worst they may be planning a more sophisticated scam and will soon be trying to establish rapport and build your trust.
Yes there are legitimately lots of people who are just starting out with Linked In, or else have badly written profiles. However, there are common signs of a fake profile.