One reason why I don't eat after 7pm is because I generally won't pick a nice broiled fish and light salad at 10:30 if I am hungry. Thats when I'm most likely to do some bad snacking. So I make a nice dinner, eat it before 7pm and don't eat after; less likely to eat something I shouldn't. Also it is proven that eating before bed will effect sleep. If you don't get a good night's sleep you are more likely to snack and eat bad things during the next day.
But everyone is different and some maybe more tolerable to snacking before bed. Personally what I eat before bed just sits on my stomach and makes my night long and uncomfortable. And I generally feel sluggish in the morning but that's me.