I'm just saying that the stretching of spacetime can be mimicked by an intrinsic weakening process. If a redshift of light can be attached to the former, then why not also to the latter?

Looking again at my analogy, is there any way to distinguish (as far as wave effects are concerned) between the situation of the wires being made thinner ('stretched') through expansion and the situation where the wires are getting thinner through some sort of erosion?