The idea behind net carbs is to only count what your body absorbs.
However, fiber consists of both soluble and insoluble fibers. Your body does absorb a percentage of soluble fiber, so technically, some percentage of total fiber should count. So net carbs isn't exactly precise.
Also, many labels "hide" sugar alcohols inside net carbs, so if avoiding those, you want to know that.
Finally, yogurt (and other fermented foods) overreport carbs because the method of calculation is via subtraction (total calories minus protein calories and fat calories = assumed calories for carb), so the lactic acid gets counted as carbs although it isn't.
Really, it depends on why you're counting. If you mostly eat the same foods, net or not doesn't really matter as long as you're consistent. If about half your carbs are fiber, then deciding to eat 50g net carb is the same as eating 100g total carb, but the total is easier to figure.
I count to dose insulin and find it simpler to just count all carbs and not have to mess with subtraction.