Whaaaaaaaat. Thats not true by any means.
True hiphop is about freedom that means you can dance whatever you want to whatever music you want. It can be break beat, funk, rap, trap, dnb, "radio songs", metal really anything you wish. If someone says it's stupid then they have no idea about hiphop culture at all. Ofc there are some kinds of music linked to hiphop but no one will have problem if you like something else ;)