Provenance and debugging. It would be quite possible to record the fact that this set of triples, G, were obtained by dereferencing this uri N, at a certain time, from a certain place, with a request that looked like this and a response that had these headers and response code. The class of information that is kept for [0]. If N appeared in G, that could lead directly to inferences involving the provenance information. If later reasoning is concerned at all with the trustworthiness or up-to-dateness of the data it could look at this as well.

Keeping this quantity of information around might quickly turn out to be too data-intensive to be practical, but that's more of an engineering question. I think it does make some sense to do this in principle at least.