There was music (some of it 'great'...) before streaming, or charts, or even sales statistics. There is music (some of it 'great'...) in every language and culture the World over. Music is not restricted to being played on the radio. Music, by its very nature ephemeral, gone as soon as it's produced. If it's 'great' enough, it will be repeated, or at least remembered, for far longer than its original existence, and perhaps, nowadays, recorded for another day. Much of modern music, just like past music, had no further pretension that to be entertaining at the time produced, and thus disposable like a paper tissue. They may have their value, but would not be considered 'great'. More rare are pieces that are worth preserving, to maybe become 'great' in the fullness of time.