For the very same reasons that they choose not to embrace the deaf community on a one-to-one basis for the benefit of their child. I would suggest that it is a reluctance to confront and deal with their own issues regarding their child's deafness, and instead, make a choice to blame their lack of personal honesty and insight on others.
And that is not an accusation. It is an observation. From both a hearing parent, and a professional trained to see the nuances of human behavior and attitude.
