There's a big difference between someone going on a diet to lose pounds, fully anticipating that they'll end the diet someday, and someone who has adopted as a way of eating.

Sure, if you're going to be on it for 3 months then you're probably not going to be intellectually curious about how you can make the diet tasty and find things to replace the stuff you miss.

If you're going to be on it for life, then you find a way to fit it into your life and enjoy it.