almost everything in biology is on some kind of continuum, any two people are probably facing situations of different degrees. This is pretty much true of all things that may or may not be described as addictions. Even to take the most classic case, there are countless people who got hooked on opiates or heroin and one day just decided to stop on another day, and just do, and countless others who struggled helplessly until it kills them (plus almost every situation in between). Those two groups undoubtedly have very different bio/neuro chemistry going on. We know the same is true with alcohol and it's probably true for everything else that people find themselves doing compulsively. There is always a natural tendency to extrapolate one person's/groups example as the guide for advice to someone else but that's always tricky business.
to the degree I will contradict myself though, I'd agree with your post generally - for the average person with a moderate amount of weight to lose, a lifestyle shift is the best way to make a change in diet stick.