That's cos they aint got a frigging clue what they're on about Bake!
I would like to think that even without my experiences of disability that I would still be horrified by this bile, even without understnading the impact such comments have on disabled children and their carers (before I had my boys I worked voluntarily in a special needs school)
However I think there are a small minority who just have no concept and no desire to learn, preferring to remain ignorant and deluded in their assumption that this vile diatribe is acceptable on any level of humanity.