As per the article, games are highly stimulating. For children and even adults (me in particular), time slips away and 12 or more hours have been spent playing games. This is especially pronounced with ADHD.
No matter how much good video games do for the brain, 12 hours remained fixed in front of a console or PC is not healthy. There have been cases of DVT due to bad sitting positions and maybe 4 hours spent on a game.
The other issue is that, if you are prone to hyper focus, you ignore your responsibilities, including using the toilet or eating. For so e people, games ARE that captivating.
As a funny but also quite sad story, my fiancée bought a second hand PS3, which I protested. Each successive weekend, I spent around 24 hours each completing game after game. She wasn't pleased. Mainly because I ignored her, contributing absolutely nothing to household chores, and partly because she was excited to play the games.
A good deal is that I can play games if I want to once the kids are in bed. I have Half Life 2 half completed, which is a bloody captivating game. I do, however, try to focus on other highly stimulating activities that don't entrance me for large blocks of time.
As a side-note, programming has a similar effect. I'd argue that was far more productive. This actually led on directly from gaming so I can't complain much.
EDIT: my autocorrect seems to be on a rampage lately. This one takes the biscuit though: "using the toilet of eating".