Why has mainstream rock quality declined over the last couple of years?

i remeber not to long ago decent badns like panic!at the disco, the red jumpsuit apparatus, the used, puddle of mudd, 30 seconds to mars and paramore used to give me a little bit to look forward to on the radio, but now it seems only nonsense like lady gaga, demi lavato and hip/hop and r&b get all the attention. why is this? and also wat are some decent bands to research anything from fall out boy to bring me the horizon.