yeah, Mere is pretty hardcore that way. All of the tours are completely clean, including smoking and alcohol while on the bus or at the venue.
I think creativity is often the restatement of assimilated ideas within new lines of context. I think where drugs might become a creative tool is at the point of pulling those assimilated ideas out of their original context, i.e. "A Bass plays the root note" <puff puff> "The bass will now be scraped with a dry sponge along the low strings, amplified through a megaphone, and reamped through an ampeg to become the sampled shaker throughout the bridge."
On a side note, I studied for 2 years with a piano player here in LA named Terry Trotter "He's the guy who plays all the Will and Grace piano cuts". His first gig was in NYC, and he was hired by Bill Evans' manager to be at every gig the Bill played, and to step in and play the piano if Evans was ever too stoned on Heroin to make his arms move. So there is that side.
He said he once watched Evans play an entire set with his right arm paralyzed. He played the whole things with just his left hand, and it was brilliant. So there is also that.
-sm