It was basically "throwaway code" which was written in a hurry for a prototype that was not expected to have a long life. This kind of parsing was (is?) very common in the video game industry, and quite easy to author in C++, so it would have been the first tool the developers reached for to implement a real-time network protocol.

The evolution was hardcoded -> message template -> "Liberación" which allows the protocol to tolerate unknown fields, and thus be future-compatible, much like Protobuf does.

Source: worked on the Liberación project.