The borderlands where someone has stiffened their resolve by slight intake of alcohol or increased their focus on a singular thing by cannabis so as to be claimed to be a help to fight better is only inches away from playing worse. In fact, anyone playing under the influence will according to emperical evidence have worse reflexes, worse coordination, worse cognitive ability, worse anything really, compared to playing completely fresh and sober - that is, unless they are addicts, but then they are also playing worse when sober, than they would otherwise, and the intoxication only helps to shake off the withdrawal symptoms, near permanent or not.
I know a lot of people who have claimed this but they have all been either addicts to some degree or another, or they have performed inconsistently, in any instance.
Go smoke some Afghan hashish on a bong and tell me you play better - you don't. It's not like the real battlefield where insobriety can work as a lever for courage and pain relief.
More fun and relaxing, though? Sure.