Since fat makes up about 65% of my daily Caloric intake, I eat fats with both proteins and carbs. Fats are naturally packaged with most protein foods, so I don't try to break them apart from one another. Some carb foods have fat and some don't, but to slow down the digestion of carbs, fats are good.

I think the issue is doing a lot fat and carbs together. Since I eat low carb, there's no need to be super concerned about fat restriction. If I ate a bunch of carbs, I wouldn't need as much energy from fat, and fat metabolism would be hampered by the immediate need to metabolize all those carbs. When eating low carb, though, you need to get your food energy from somewhere. Fat fits the bill.