Defend his actions all you like all I see are the same excuses Best or Gascoigne and others had wheeled out for them, they got away with it in part while they played, however, it soon unraveled. Nowdays fitness is such a key part to playing attributes, a player as gifted as Barkley cannot just rely on footballing ability in the modern game, he needs to be physically at his peak while in competitive matches all of the time, drink or no drink, the irregular sleep patterns are have enough.
It's makes sense why he got dropped by Koemen and lost England exposure, he has distractions that don't fit with modern football.