It's funny you bring this up. I have has a friend swear by Dizzie's methods and now a cousin is too! But both of them have openly posted Dizzie's information on my Facebook wall!
So I found a random article about how 20 years ago we as a society were not that concerned with babies not sleeping on demand (basically) and that how we've bowed to social pressure to have a 'perfect baby'
So I posted this on my page to give the others the hint!
But the saddest part for me is every. single. time. I text my friend to catch up, on weekends usually, she replies it has to be before 11am or after 2pm, because her DS is sleeping and can only sleep at home. He's now nearly 24 mths!
And my cousin, that's a whole other thread!

I would just give your friend exposure to the other options. And gently say I found a few things that you might want to try.