That's really strange - I don't think the writer did much research. Bill Wyman of the Rolling Stones was by far the busiest - Keith & Mick had to sneak it around their so-called girlfriends all the time, models and actresses and such. And in "normal" bands, the lead guitarist, singer and drummer do most of the serious drugs, and the bass players are the guys who don't pass out. If you have any memory at all of great parties, you know what that means. And chick singers are almost always banging the bass player, unless it's country, where they're banging the steel guitarist. Because they're singers, and they know singers are insane. One of Steven Tyler's great complaints in his book was about how many chicks he didn't get, because he had to do drugs instead.
Sex, Drugs and Rock 'n' Roll - you can only be seriously dedicated to any two of them at a time.