the 'better than the Beatles' problem is at least superficially compelling. When Benadryl was discovered, the bar for allergy drugs was pretty low. Today you have to improve on drugs that have several advantages over Benadryl (and cost ~$0.50 a day OTC in the US).
https://en.wikipedia.org/wiki/Eroom%27s_Law
the 'better than the Beatles' problem is at least superficially compelling. When Benadryl was discovered, the bar for allergy drugs was pretty low. Today you have to improve on drugs that have several advantages over Benadryl (and cost ~$0.50 a day OTC in the US).