Oscar,
this specific issue has been discussed quite extensively on this forum in the aftermath of the 2015 Index. I think it is especially problematic in the National Statistics dataset, as the definition is so broad:
Key national statistics on demographic and economic indicators such as Gross Domestic Product (GDP), or unemployment and population statistics.
that it is unlikely for so many different kinds of data to be contained in a single dataset. That would not even be considered a good practice anyway. So, I think that for this dataset it should be expected that submitters of all countries will find multiple different datasets.