Fats have a benefit over carbohydrates in that they're hydrophobic so they absorb much more quickly through membranes (e.g. can be used as energy sources better) especially in the brain because things have to pass through the blood brain barrier. Hydrophilic substances needed to be pumped across it unlike most hydrophobics
Body needs insulin or glut4 receptors to drive glucose into cells.
Most aerobic metabolism runs off fat stores too so our bodies are built to run on fat. I don't see why it's a contradiction or anything. It is what it is.... MCTs are even more preferential than long chain but some short chains are easily metabolized too like butyric acid (derivatives of BA are neurotransmitters like GABA).