The point is that if those were effective at providing all the rights necessary for a family, then there is no need for married heteros to have anything other than a will & poa.<quoted text>
You are right. They don't who said they did?
Just because Wills, Medical Directives or POA and other legal documents were not handled in a legal matter by some individuals does not mean they are not good and effective vechicel. Some people feel wills fail them when they don't get their way. I'd have to see the individual case to make a specific determination whether they were screwed by the system or not.
Your ignorance is showing again.