There is no advantage to having different one-way latencies, as long as the round trip time is held constant. A player with all delay on sending TO the server

There is no advantage to having different one-way latencies, as long as the round trip time is held constant. A player with all delay on sending TO the server will have to wait for their actions to be received, whereas the player with a large delay on receiving FROM the server will be reacting to 'old' states. These two situations happen to be indistinguishable.