My read of it is that they aren't specifically talking about weight loss diets, but general good health, so a 2000 calorie diet is the typical "standard" adult diet (that's what most of the RDA's are based upon - then you adjust those according to what calorie level is appropriate for your individual weight maintenance needs.)
Their findings aren't really anything new, but merely a continuation of the evolution of nutrition science, which still holds that for optimum health we need a balance of various micro and macro nutrients, spread through the various food groups.
One of the salient points they bring up, one that I have long followed, is that the quality of the food, whether they be carbs, fats or proteins, is a lot more important than the quantity. This is why these fad diets that hold to certain magical macro counts or ratios tend to be pretty silly - and we see that sometime in these forums. Some may hold to that magical 20, 30 or 40g carb count, and then skip the "carbs" in that apple or broccoli to save up for that Snickers bar in their carb budget.
I never worried about carb or fat counts while I was losing (and still don't) as the restricted calories and protein minima in the early post op world took care of that; rather I just worked to maintain as healthy a balance of foods as I reasonably could within my calorie budget; on average I ran around 100g of carbohydrates per day, but I was still working to slow down the loss rate at the six month mark. I actually increased my average carb count selectively at around the 4 month mark to promote better exercise endurance, and my weight loss trends improved (they stayed steady rather than declined as is typical) as that probably helped promote a marginally better calorie burn rate.
The other benefit of using a more "normal" diet during the weight loss phase is that the transition to maintenance was much easier, as my maintenance diet is fundamentally the same as the "loss" diet - just more calories from the non-protein side of the diet spectrum (as protein should already be at a maintenance level during the loss phase.) I didn't have to learn a new diet for maintenance, nor have to switch diets to lose again if needed - just adjust the calories as needed.