Why Do Classic Rock Fans (I'm a Classic Rock fan also) attack People like Ke$ha and Justin Bieber?

Honestly head back to the 1980s (Madonna), 70s (Disco), 60s (******* Sonny and Cher) or whenever, you'll here this crappy pop music. What i don't understand is, is how Kesha and Justin Bieber are harassed for the death of Rock N' Roll, why don't you blame today's rock bands instead of todays Pop Bands?