Regarding music, why do people compare yesterday's gold to today's crap?

Well - I was a teenager in the 70s and the music was great. There was its true a lot of garbage to. I think if we compare the best of today with the best of then the old stuff wins. The baby boom after ww2 caused an unusual number of young people by the mid to late 60s and that imbalance caused the culture that spawned the music. If that was the crest of the wave, today the wave has largely broken and is washing up on the beach. In my opinion the first, great, stage in the evolution of rock music ended in about 1977 when the record companys pulled the plug on ever more expensive records. That and disco. I think it was a period like the Italian Renaissance - a flowering that went on for a brief, wonderful period, but then naturally died away. What is the next great thing? Time will tell.