I do it for a few reasons
(1) it's very easy for me to not eat during the day, I'm just not hungry or thinking about food
(2) it's very difficult for me to not snack at nighttime
(3) in order to balance the calories and make sure my nighttime eating doesn't make me fat, I just skip the carbs/fats throughout the day, when I'm not hungry anyways, so that I can eat when I want to at night
(4) carbs (or really excess calories other than protein) during the day makes me lose motivation, makes me tired, etc
(5) carbs at night help me relax and sleep and also help me recover after my afternoon workouts