Have you tried running an anonymous Facebook account in the past decade? Facebook lets you use it for a few weeks (or months), then suddenly refuses to let you in unless you provide identifying information that it never asked for before, and refuses to give you your data back until you “verify it's you” (might be quoting Google or Microsoft there, but Facebook has similar wording) even though they have no records with which to compare it to, so that can't possibly be a valid justification.

It is against linkedin's policies to use a fake name. While facebook accounts require a real name you can create additonal profiles that use pseudodnyms and can not be traced back to your real name.