Banning gambling might help to reduce the gambling addiction, but how significant is always remain questionable. On other hand, there are always thousand ways to rome. It means gamblers who being addicted will always looking for a site to gambling.
Yes, it's true that players will look for other gambling opportunities, but this only applies to gambling addicts. The rest of the citizens, most of whom are law-abiding, will not violate laws prohibiting gambling and refrain from playing.