Egg white contains ovomucin which is an anti-protease inhibiting the action of the trypsin (digestive enzyme) in the small intestine. But ovomucin is itself inactivated by the pepsin of the stomach.
My guess is that the egg white because of its liquid state leaves the stomach too quickly before the pepsin has the time to fully inactivate the ovomucin. The solution is to slow down the stomach emptying time in order to promote more complete digestion by absorbing some extra fat.
But raw eggs do interfere with the absorbtion of some vitamins (Biotin and B12) but it's not an issue if your diet is varied and you don't consume raw eggs at every meal.
BTW raw egg whites digestibility is roughly between 50% and 65%, not that bad (the proportion of absorbed protein from beef for instance is roughly at 75%) Yolk is more digestible raw than cooked.
Raw Egg Lova,