I'm pretty certain that the article means it's unlikely to produce a major reduction in the number of detectable unwanted pregnancies. And if it can't even accomplish that, what's the point?
I wish liberals could somehow be made to acknowledge that people are much more likely to engage in reckless behavior if they think it safe than if they think it dangerous; efforts to make reckless danger 'safer' will result in more people engaging in it. A ledge with a railing that is likely to fail if leaned upon may be far more dangerous than a ledge with no railing at all.
I guess that's what I was getting at. If people think they can just eliminate the complication of a baby with that kind of ease, they're not going to do anything to avoid getting pregnant.