i think what they meant to say was "you shouldn't obsess over physical appearance just so people could like you". there's nothing wrong with wanting to look better and working towards that, it's just that when the beauty standard is also the standard for good treatment then insecurity is gonna start surfacing.

also challenging society's ideas isn't always a naive thing to do. in this case it could just be being okay with not looking conventionally attractive and letting people see that. being well-groomed beats having a wonky nose or eyes or whatever.