Maybe it's a case of horses for courses with musicians. I am fairly sure that in my own case I play better without any alcohol or dope at all. Sometimes I will take a pint towards the end of my final set. Some of the musicians I play with drink a pint or two during the gig - to no discernable disadvantage. Performers who are discernably drunk or stoned on stage are usually a pain in the neck to work with and (imo) look like amateurish buffoons to their audience.
To say baldly that The Beatles - or anyone else - "cheated" by using drugs is a gross over-simplification of what was happening in their lives at the time. Drugs were part of a culture which, in the view of many of us, produced extraordinary music. I think there is little profit in speculating upon whether that would or would not have happened had there been no drugs.