Why do people act like beauty standards are ridiculous? They are like exactly what is most healthy?

Heterosexual body standards for both genders almost identically reflect what is ideally healthy. In shape and in the middle of a normal BMI and low body fat but not too low. U can’t get healthier than the beauty standard for both genders. And ok sure u see some models who are slightly underweight and a few who are downright anorexic but those ones are almost always modeling clothes and never their bodies and being slightly underweight is not dramatically unhealthy like everyone wants to make it out to be. U have to be very underweight for it to become a serious health risk as a young person.
Why do people act like beauty standards are ridiculous? They are like exactly what is most healthy?
Post Opinion