I really have to ask if you are serious with that question.
I honestly don't think so, but I'll play along with one example.
Because of just one protection of marriage, my next of kin is not determined by whose sperm knocked up my mamma and how many other rug rats she squeezed out. Therefore if I am in the hospital, unconscious and in need of medical care requiring consent, or possibly in need of a decision whether cessation of medical care is appropriate, I have my chosen NOK, my wife in whose hands I willingly place my life to make that decision, and not my hillbilly redneck, brokeass and looking for a windfall, blood relatives.
Was that question supposed to be some kind of Socratic irony?