Our progress in information theory has been in response to our communication devices. It started with Morse and the desire to increase the amount of information that could be carried on a wire. Some of the theory is surprising, and came into its own as recently as WW II. It would be difficult to devise theory for devices that have not been imagined.
ETs have probably been monitoring our radio emissions for decades. The 1950's and 1960's were hotbeds of UFO activity. Then the 70's hit and the sightings dropped dramatically. They probably got an earful of Disco music and decided we needed another 100 years or so before we were ready for contact. If Elvis and the Beatles ever come back in a big way, maybe they'll return.