Joe,
There is so much misinformation on carbohydrates and energy metabolism and I speculate that part of this is due to the fact that removing carbohydrates from the food supplly is far easier than removing fat from the food supply. Again purely speculative but try going on a low fat diet and a low carbohydrate diet and see which one is easier to navigate in all scenarios.
To answer your question, if you eat high glycemic index carbohydrates (e.g. sugar, white bread, etc) by themselves without any protein or fat source then you will get a rapid rise in blood glucose levels followed by a rapid fall in blood glucose levels (i.e. the "food coma"). If you add fat and protein into the meal (which most of us do) that blunts that response by slowing down the digestion process, thus slowing down the release of glucose into the blood stream. So this is where the feelings of lethargy associated with a high carbohydrate intake come from. Additionally, carbohydrate need is dictated by the intensity of an activity, to a certain extent. We are always using fats, carbohydrates, and protein for energy and are never just burning one. Now when we lift we need carbohydrates because there is some anaerobic glycolysis going on as we compile more and more sets of whole body exercise. Fats contribute little to nothing to this type of training so it's not a very good fuel source for a strength trainee. Therefore, the best macro split for a strength trainee is going to consist of high protein/low fat/high carbohydrate. Does this make sense?
PS - Did Super Squats back in 08'. Fun times.