I stick to a fairly consistent policy about accepting invitations to LinkedIn. I hardly ever accept invitations from people I’ve never met in person. I realize some people use LinkedIn like an extended address book. I use the site to keep ties with people for whom I can vouch or testify to their technical skills or interests. I never want to look at my LinkedIn contacts list and ask myself “Who’s that again?” I expect some people might not care for this policy, but that’s the way I use it.”]
Source: https://taosecurity.blogspot.com/2006/09/personal-linkedin-policy.html