It might be interesting to see the study carried other way round. How many people with mental problems can turn into game addict. As it is said in the article "While these kids were more likely to have behavioral problems to begin with" there were already mental problems. But yes uncontrolled gaming made it worse or maybe just helped the problem to stand out. Same is true with anything you can imagine. Alcohol, cigarettes, food,
... Should we ban these? No, we put some restrictions on availability of some of them depending on how much damage it can cause. Some of them are completely uncontrolled.
Parents should watch their kids if they don't have any problems. Not just checking if they have cold. Sometimes starting to play too much might be just indication that there is something wrong with kid's surrounding. Either in school or anywhere else. What you think will happen when kid is bullied? It will start avoiding people and eventually finds that playing games is much more satisfactory than playing with "friends".
And sometimes it is just big misunderstanding. As it was in movie Role Models.