I think there is a overly romanticised view of drugs when it comes to rock 'n' roll. Over the years I have worked with a handful of drug users and they are generally a pain in the **** - not as creative as they think they are and pretty unreliable. In the 90s, we had a guitarist who was permanently smoking weed ("only weed") and he'd have to give me his money to cover rehearsals at the start of the month or he'd spend it on weed. We'd then get to middle to later in the month and he'd be calling me up asking for a loan. Every month it was the same, we'd debate it for an hour with me reminding him of what happens every time, only for history to repeat - he'd then get angry with me when I asked for it back "it was just a fiver, not a tenner", only to eventually remember that I wasn't a liar and it was as I had written it down. Unsurprisingly, I don't miss that!
These days I work with a few musicians who have issues around alcohol and I have to say it is the same. Some really talented players junking 1/2 a day of recording because they listen to the play back. I find it staggering when good musicians practice all the time and then when they go out, they blow it for themselves.
I hasten to add most musicians I work with these days are focussed and creative. Have a pint, smoke a spliff (if you have to) but just keep your act together!