The concern is to get away from content-free statements, such as
light is a wave, when the idea of a wave is not spelt out. Waves are theoretical constructs, a whole intellectual mechanism or apparatus, useful for describing some phenomena. The key question is whether the idea of delayed mimicry of periodic motion is an essential piece of reasoning, or not. If not, then I suspect we continue to do little more than categorise – useful, but not defensible as a central occupation in an education in physics. Any trace of framing the descriptions as if one is discussing particles or other stuff moving from source to detector needs to be lost. This has implications for any courteous introduction to the idea of photons, not dealt with here (it is possible to construct an intelligible learning journey, without discontinuous jumps).