are you Korean?
they were not viewed as a serious musical group compared to others of their peers who focussed only on music but they were far from being considered as a joke. that's just something i-fans like you love to throw around all the time.
believe it or not but SJ had been called as "national group" several times by Korean media in any number of occasions in the past but no one made a huge fuss about it. otherwise certain other fandoms would go ballistic