1. Attention spans are shorter (most often cited reason)
2. Human population is much larger. Less humans means less talented people. When Mozart was alive, he (and very few others) could monopolize the entire musical scene since the competition wasn’t good enough (and was spread out across geography and time). But today there are more humans, and the internet allows talent to accrue. With higher talent density, it makes sense that each individual can only capture a smaller share of the attention market. (Tangent: more humans lead to more ideas. There’s less repitition (less variations). Density of new ideas is higher)
3. Only the long stuff survives. Eg. what percentage of the greatest artists’ (Shakespeare, Mozart, Back, …) work actually lived to today? Most is lost.
4. Internet. Faster to change what you’re currently consuming.