In what world are you living? Being obese is and always has been frowned upon. There is a small faction of people who believe that nobody should be treated poorly for having a body that doesn't fit an ideal. You specifically say that body positivity "makes people feel good about obesity". Which, said another way, seems like you think "people should feel bad if they are fat". Why would you wish for someone to feel bad? Assuming you believe that fatness is failing caused by something wrong with a person, do you also believe that depressed people should feel bad because there is something wrong with them? Do you believe people with PTSD should feel bad because there is something wrong with them?