This is absolutely horrible advice. Alienating yourself from all of your friends simply because you don't want to drink the same things as them is not a good idea.
If you don't want alcohol, then just don't drink it? I have been to many, many, many music festivals, parties, etc. and not drank anything. I can't imagine just exiling myself from all of my friends instead of simply not drinking something.
(Obviously if you have a medical condition or something, or a history of addiction, then this might not apply)
edit: there are many replies to me talking about addiction and accusing me of encouraging an addict to engage with their addiction. I'm not. I said it above, but if you have a history of addiction, or if this is an addiction problem, obviously this advice does not apply, and you should distance yourself from addicts.