Seems like something that would make almost zero real world difference. The advantage to me would be that you can more quickly pull the hub apart and reassemble it.
Then it begs the question of why not just use the newer GM knuckles that take unit bearings? They probably weigh less even than the typical spindle setup.
Oiled hubs are a thing in many applications. Nearly every full float truck axle technically uses an oiled hub, although you'll find people like to assemble them with grease anyway. The downside to oil is the seals and sealing surface need to be better, and if the hub is oiled independently then the oil level must be checked and serviced on a regular basis. Bearings prefer oil over grease; grease is a compromise to make up for poor oiling design, sealing issues, or lack/cost of servicing options.