I think they pointed out that based on their experience, it's probably not even possible to separate correlation from causation cleanly and I think I agree. Even though I never smoked I spent a lot of time around people who did and I could have told you even at age 14 before they took their first puff that they were, on average, much more likely to exhibit some of the things the study listed as "findings" like "more likely not to have a job", etc.