Sometimes it takes more than starting a new hobby yo stop addiction, the reason why I'm saying this is because there are people that I know that started learning how to play videogames just to quit gambling addiction but somehow they still find theirself back to gambling. It's all about having self control and being able to stand on your decisions of not going back to it, distracting your mind with a hobby might not be enough
Starting a hobby or trying to divert their attention and brain towards something else can be helpful if a person is at the initial stage of their gambling addiction, and is still able to somehow control the urge and stay away from gambling if they force themselves. So, if they start doing something else that they possibly like doing in general, they might be able to get rid of the gambling addiction. For me, for example, I love playing video games, have loved them since I was a kid, so if I'm getting addicted to gambling, and I'm given the opportunity to play video games whenever I want, I will surely be able to stay away from gambling with that method.
But as you said, it might also depend on a person's nature. Some people are not easily drawn towards things, like they might try and do something else as a hobby to avoid gambling, but if they are not drawn by the new activity, it wouldn't take them much time to get back to gambling because they simply can't stop thinking about it at all, and when you mind isn't present in something you are doing, you won't be able to continue doing that for very long.
Thus, it's all about how a person behaves in general whether such things can help them or not getting rid of their gambling addiction.