A theory, yes. Those who say “only a theory” tend to confuse theory with hypothesis, which is much looser. A theory is a coherent set of principles serving to explain a range of phenomena. Emphasis on coherent, meaning not only internally consistent, but also consistent with related knowledge. The road from hypothesis to theory can be long and tortuous.
My question was meant to be rhetorical in response to the OP.
We have many things labelled to be a theory that are complete enough to be acceptable answers while still being considered relatively incoherent or insufficient to science.
