I guess its the same as people forming relationships with animals (not sexual obviously), I don't understand how people can form companionship style relationships with animals, I mean some people REALLY love their animals.
I would imagine thats true, its a bit like children at play in that respect I think.
If you read into it, some of those people have used these dolls to replace a lost loved one, I can imagine if you've lost the "love of your life", you'd find it tough to replace them with another human, and look for companionship elsewhere.