Cross-Feeding

So today on Good Morning America, there was a clip about breast-feeding someone else's baby.  In the clip a woman tried to calm down her best friend's 3 month old baby for a long while and realized that he really just wanted to nurse.  So she nursed him and he was better.  Her friend doesn't have any problem with it.  She knows her friend well (that she doesn't have any disease or drug problems) and wants her baby to have breast milk.  So she is fine with it happening from time to time when she isn't available to nurse him herself.

Apparently, 46% of Americans label breast feeding someone else's baby as Disgusting or Weird.  Obviously I haven't experienced breast feeding personally.  But at this point I do see it as just feeding a baby.  I don't understand how that could be gross.  Woman have done this for years.  That is what wet-nurses were for.    Isn't it better for a baby to be nursed by another woman than to be hungry and upset (if they don't take bottles).  Perhaps I'll change my mind on this when I have my own baby.  But I do think that I wouldn't mind my sister or very-close friend stepping in for me if I were not available.  What do you think?