It is common that the elder couldn't accept the younger.In my opnion,the so called post-90s' phenomeno can't represent all the post-90s.
Obviously post-90s in Peking University won't behave like what you have say above.
Different people have different values,post-90s is a diverse group.Maybe they have more personality than others in statistics,that's a good thing.Because our society should include people with different sense of value doing different things.Then the society can develop.