A more interesting question might be: what is the evolutionary pressure that caused convergence towards aging across essentially all multicellular living things on earth?
But I'm not denying that breaking down and entropy is an almost universal fact of life for most of life.
and I agree that from an evolutionary perspective there's no point repairing the body after the sort of population average procreation age. and in fact I think someone else mentioned in this thread that you know there's some organisms that die immediately after procreating. And I'm also not disputing that repair mechanisms and things like telomeres have a genetic origin... that seems obvious.
However this sort of decay behavior and repair behavior is not universal there are some things that are a lot more durable but even if we assume that it's universal, i don't think you can tell or I can tell whether, nor the extent to which, decay is a disease or genetically evolved solution to some problem that we don't understand yet, or some complex interaction of the two.
The possibilities of some of the potential consequences of immortality have been discussed in this thread and people have proposed aging as a genetic solution to that, and an explanation for why agelessness which, on the face of it seems like it would be adaptive, has not evolved. So I honestly don't think we know the degree to which aging or agelessness is genetic or is diseased, or a complex of both. And I don't think your relatively simple, but still on some level convincing, example establishes that either way.