Yeah but that has absolutely nothing to do with the argument. The issue is over quality of music, which has nothing to do with availability. Now if we were discussing the quality of mainstream music, then I would agree, the sixties were far superior. Although we have to keep in mind, what gets played on the radio from the sixties now is very different from what was played back then. Jimi Hendrix, for example, wasn't all that popular back then compared to what he's grown to today. And banRAB that may seem somewhat mainstream now, or at least very close to the surface of the underground, like The Velvet Underground, were very unpopular at the time.
In conclusion, timeframes are moot. Every decade has its fair share of great music, and shit. And in 50 years, on a forum just like this, ALL of our opinions will be obsolete, because fans of music from the 2030's will be arguing with people who thought the last good record ever made was "The Future" by the band ROBOTS, made in 2016.