He also repeats that binary protocols have the downside that you need to "have the spec in front of you" to interpret them... but network traffic is virtually n

He also repeats that binary protocols have the downside that you need to "have the spec in front of you" to interpret them... but network traffic is virtually never inspected by humans without the assistance of a protocol dissector that will add the descriptions, parse numbers, and so on for you. There is clearly an efficiency downside to packing this description into the messages themselves when the recipient software will necessarily have the protocol information necessary to decode it.