I don't think this is new. The idea always was that proto-humans had to live in an environment rich with energy dense food (fruit) prior to growing a brain large enough to figure out how to make barbeque. Otherwise you never get to the barbeque capable brain. The whole point of making fire and therefore consuming cooked meat is that now you can migrate to places that don't have abundant sources of energy dense food.

If you’re constantly moving sugar is a necessity for maintaining glycogen. There’s nothing inherently wrong with any food type, it’s all about context.

There’s many theories but one that I learned was that women and children provides the bulk of the calories for Early Humans. While the men went out and hunted for meat they also relied on the fruit harvested by the women and children. That would give them the energy necessary for trekking and hunting.