Should I join LinkedIn?

I have to look for a job or start making some money soon. I don’t really want to join linked in but I hear that’s what one must do? I keep getting invites even though I’ve never opened an account, either from people I never heard of or people I know very well that can’t be bothered to go on facebook or answer an email- I also don’t want to get a bunch of email notifications, it just sounds like a drag. Is it necessary?