This has puzzled me for years, in the crypto community having a LinkedIn profile seem to be the communities way of saying "Yep you're a legit person".
It certainly doesn't make you 100% legit. But I had quite similar dilemma at some point in the past when 21.co allowed people withdraw only if they link their LinkedIn profile.
Which was odd to me because although I am real and legit, I managed to live until now without LinkedIn.
So as said, LinkedIn can most probably be also faked, but also probably most won't do that since they don't see any reason to do that. Except the scammers...