So much confusion here.
First, can we try to take the discussion in a scientific direction ? The specific mistakes being committed here are :
1. Conflation between carbohydrates in diet vs in blood as sugar vs glycogen e.g. in muscle/liver. The original question was about diet.
2. "Better" and "good" energy sources ? Better and good are highly unscientific terms. Even "essential" was largely discussed without a concrete definition.
3. Different energy sources may have different efficacies in different situations - some to recover from illness, some to be energetic in daily life, some for heavy workouts*.
Fat is a good source of energy for the rest of the body, but not for the brain.
Mistake number 1 and 2.
Mistake number 1. The vast majority of the document is about blood glucose , a lot of it is about even more specifically : brain glucose as is also evident from the title. Only one reference about diet is for rats, I hope we are talking about humans.
Read the basic biology books/wiki & any balanced diet recommendations from major medical & educational institutions. Or something simpler to understand, you know what is used in the drip to severely dehydrated patients in hospitals, glucose drip not liquid fat drip
Mistake number 1 and 3
Selling grains/legumes is more profitable or selling meat & milk?
Right - so politics and business. While this is complicated and both plant based and animal based food industries have unfair advantages. I don't profess to know enough to calculate both unfair advantages everywhere and find out which is greater. Given the complication and secrecy of these things it can be argued without much difficulty that no one else knows it either. One thing missed here is the "food security" of countries that pushed for grain stores in countries reaching astronomical proportions. The story is about the period of the Cold War, which happened soon after world wars when even developed countries faced food shortages and had to ration food. Grains can be stored much more easily for much longer than meat and dairy. So governments wanted grains to be grown a lot, whether or not people eat it in the short term. This led to, e.g. the payment to corn farmers in the US, even when they do not grow anything. The idea is to have the capacity to grow grains in case it is needed in times of war. This at least partly led to the explosion of corn stuff in the US - including ultra cheap sugar syrup made from it. And an explosion of grain in the world.
The government interest in people eating grains for their war preparation efforts has at least led to some lobbying in government agencies recommending more grain than may be good for people. Businesses are powerful, but governments and their covert intentions can be stronger in some contexts.
Fats being better source of energy for the muscles involved in intense workouts.
Mistake number 2 and 3, though mistake number 1 is also lurking just under the surface. Moreover, intense workouts were not even the subject of this discussion before you first mentioned lifts and sprints
here.
* I have evidence that the different energy sources
do have different efficacies, but the discussion here is too unscientific to mention any of that.
