There are many trends in dieting, one has seemed to have stuck around - cutting carbs drastically or completely.
Firstly, by cutting carbohydrates excessively you're going to notice a drop in performance. As this happens your ability to achieve overload across a multiple of rep ranges diminishes, ultimately increasing the risk of muscle loss. Being depleted in carbohydrates also tends to make your muscles look very flat which alters the aesthetics of any physique.
From a fat loss standpoint, the further you get into a diet where you've been in a calorie deficit there will be a natural decline in metabolic activity for most people.
Carbohydrates actually help stimulate your thyroid and metabolism, so being in a deficit with very small amounts of carbohydrates for prolonged periods of time can become problematic. This is where people tend to hit a wall and are unable to get past the plateau, because they've cut their carbohydrates too soon.
Yes, you will often need to taper calories once you get deeper into a diet. However, done the right way it should be sustainable and progressive whereby carbohydrates are properly managed. This way the metabolism is protected and your progress isn't inconsistent. This is where refeeds can help, when done correctly.
I would never advise anyone dropping carbs completely, more like manipulate them to suit your own needs. All this no carbs after 4pm stuff does not work for everyone and most people train after 4pm so therefore a ridiculous idea.
Carbs will help you retain muscle and loose bodyfat if worked into the diet correctly.
Hope this helps.