Yes, this is possible. I'd argue though that if 2 instances of life exist (them and us), n instances must exist, (and thus some must use radio waves) because it clearly demonstrates humanity wasn't a freak septillion-to-one occurrence that shouldn't have happened.
Interesting point, but given the amount of randomness involved in evolution, the physical complexity of cognition, and the timescales involved, is it possible that even given massive numbers of cognitively advanced species in the universe, each could have such a fundamentally distinct ontological relationship to reality and model of the physical universe that even a concept as seemingly scientifically basic as a 'radio wave' would be unique to us?
This would be relevant for civilizations like ours, using waves to purposedly contact with others, but not for signals used to communicate with spaceships or colonies of the same alien civilization.
