Not to shatter any preconceived ideas you may have of what drugs are, but the caffeine in coffee is most certainly a drug.In fact, I drink a lot of coffee, which keeps me going, rather than using drugs, like some people do.
In any case, who cares what other drummers drink/take when they're playing. More power to em if they can still play how they want.
Just because some may find that drugs impair their ability, doesn't mean that others can't find it even potentially aids them.
Love a nice cold beer at a hot gig.