Parker's response to one of my queries on behalf of High Times magazine also found its way into Playboy's reportage of the same event. From my article:
South Park creators and Colorado natives Trey Parker and Matt Stone also had an unexpected take on drugs. "We wouldn't say we haven't had some good times on acid," Parker admitted. "But, on the other hand, that doesn't have much to do with the creation of the show or definitely the work of the show. You simply can't do it and churn out episodes. Unfortunately, we just don't have time for drugs anymore."
"Yeah, it's really a shame," added Stone.