Did you see the URL? QuitGamble.com Which means you should quit gambling.
The site is intended to assist people who are addicted to gambling, with all the adverse effects an addiction can cause, let alone with gambling, which usually involves large amounts of money that can be disastrous for an individual. It doesn't blame gambling as an activity, but the addiction to it, just like any other addiction, is harmful.
You have not checked the site and you make conclusion. I only read the introductory path which has no complete information and I may not be exactly be correct either. The introductory path does not talk about quitting though.
People that want people to quit addiction want addicted people to stop doing that thing that makes them addicted, like to stop smoking or gambling. It is better to stop than to continue to be addicted.
I did a quick look at the website and found a few guides and posts containing the symptoms of a gambling addiction, statistics, some general information, a few blog spots, and a happiness test, which is pretty vague and asks only a handful of questions, which are not enough to draw a conclusion.
In general, the website has useful information but certainly requires more tests, questionnaires, and content.