Well, they can sell theoretically unlimited copies of songs now, whereas back in the day every single and CD had to be manufactured physically. It's only natural that more copies of individual songs are sold now.
Why are they comparing people from other generations to singers from ours? Music changes. 90% of people in our gen don't even know any of the old artists listed above except Beatles, Bob Marley and Celine Dion. This article doesn't make sense to me.
