If you are consuming your 2000 calories diet, and it is coming from plants, you are still ingesting 2000 calories worth of carbs.....
1 kg of feathers, and 1 kg of iron, weight the same....
The feathers will be large and take more volume, while the iron will be small and more dense.
Same with foods.... if your plant based diet you are consuming 2000 worth of bio-available calories, then that is still mostly carbs...
It is healthier for sure than consuming 2000 calories through processed foods such a muffins, chips and other crap. But, still your 2000 CALORIES will come through CARBS, but they will be digested slowly due to the fiber.
But if you are ingesting 2000 bio-available calories through plants, it is most likely mostly carbs (plus some fats and protein). Insoluble fiber just goes towards your poop, and it is usually not counted under 'carbs'.