One of the many things that has occurred in the last century or so that has stemmed the flow of oral tradition is the acceleration of fashion change, mainly due to modern technology. Something comes into fashion and rapidly disappears as something else comes along to replace it. Consequently only the very memorable items take a hold whereas prior to this they had much longer to take a hold.

An example might be the minstrel troupes that started c1840, were the bees' knees for decades and didn't actually die out until the more PC 1960s.

However there is still a strong oral traditon of sorts with song. Generally only 'folk singers' and their children would count 'folk songs' in this. The typical oral repertoire contains community songs, children's rhymes, football chants, pop songs from parents' youth/own youth, TV ad jingles, school songs, hymns, popular carols