Music is a social staple, and relevant bands have become a defining cultural landmark people use to demonstrate their intellectual credibility. Whether or not you can name even a single song by Pantera or actually understand what makes Pink Floyd so simultaneously popular, innovative, and controversial, you have likely nodded along in agreement whenever either comes up in conversation.
The most notable rock bands throughout history are often recognized for their contributions to the music industry, and admittedly, you will probably get few shocked glaces if you claim not to like Led Zeppelin. No one is pretending to enjoy Nickelback or the Insane Clown Posse - given their status as some of the worst bands of all time - but some might lie about Tame Impala or the Beastie Boys.
People who lie about liking these bands do so because they know one hit song or because it gives them rock-cred to comment on someone's Black Flag tattoo. You are instantly cooler if you can talk about The Clash and Rage Against the Machine with musicians who have honed their craft, but be careful - you might be asked about your favorite album, or even the technical innovation of an unfamiliar band, and you'll be outed as a poser when you can't come up with an example.