I basically agree with you, and I have a profile on LinkedIn.

A number of companies only announce job openings on LinkedIn, and if you are looking for a job (as I am) you would handicap yourself by not having a profile there. HR departments around the World are infatuated with LinkedIn, unfortunately.

My strategy is to give LinkedIn a minimum of information, use it for job search, and filter away most of their emails.

I look forward to the day where I can close down my LinkdIn account. But until then I have to put up with it.