I think in a lot of cases, people are trying to lose weight for a specific occasion (e.g. a wedding or summer holidays), rather than thinking of the long term goals. That said, I think starting a diet gets you uses to eating less and introduces you to betterhabits, which people may be more likely to take on perhaps even subconsciously after they finish dieting, I.e. the diet is getting your body used to it and the individual takes responsibility after that to eat healthily and exercise more.
I agree so I'm working on learning moderation and portion control. I'm taking tips that I can apply in my own life to obtain a healthy weight and lifestyle.