Well I guess that's where we disagree. It's clearly offensive to make fun of a blind person for being blind, no one should do that. But I do not see how it is offensive to actual blind people to call a sighted person "blind" for refusing to use their eyes. It is of course not polite to the person I'm speaking to, but that is the point, there are plenty of times it is ok to be rude to people, such as when they're harming you. Offending purposely harmful people like bigots, racists; and negligently harmful people like inattentive drivers, people who leave knives pointing up in the dishwasher, etc presents me with no moral quandary.
I'm not sure if you're saying it's offensive to disabled people to make the comparison, offensive to the abled person you are speaking to, or both.