We've known for decades that cigarettes are addictive. We've known that opiates are addictive. We know that alcohol in excess can be addictive.

Loads of people took in that information and never became addicted (at least until the medical industry tricked them into addiction). The information "if you don't want to be addicted don't do the thing that is sure to get you addicted" is very good advice. It is irrefutable advice.

Once you're addicted it's an entirely different, much more difficult problem. But it isn't a better understanding of addiction to say "Whoa, look I used heroin at a bunch of parties and now I crave heroin, therefore you shouldn't tell people to not do drugs". It doesn't follow.