It’s just like racism and sexism and all their friends, but worse

A lot of the time, when I ask people to stop using the word "retarded," they're unsure as to how it can be hurtful. But they usually get it as soon as I point out that it's just like using race, sex, gender, sexual orientation ("gay" is usually the key), and other inherent traits as insults--except it's worse, because the percentage of people that cannot speak up for themselves is way higher in the group of people who are described by the word "retarded" than the other groups of people (grouped by race, gender, etc). Of course we have many people who are able to speak up for themselves, but this particular division has waaaay more people who canNOT than other divisions. Perhaps that's why IQism (and ableism) have gone largely unnoticed (resulting in the normalcy of words like "stupid," "lame," "crazy," etc.) while racism, sexism, and others are in the spotlight. To my horror, people are now using "autistic" and "intellectually challenged" as insults. They can't claim ignorance... Help!