Of course it's not a cure all, even the biggest proponent has never claimed that. It has indisputable results in certain medicinal situations and only someone that refuses to educate themselves on the matter would disagree.
Yes, it gets claimed all over the place.
https://www.google.com/search?q=mar...CQDg&ved=0CAsQ_AUoAw&biw=1422&bih=686&dpr=0.9