In my experience categorising tends to drive people with very rigid preconceived ideas bonkers. Such people dream up 'theories' and then expect the evidence to support those theories. Often, when the evidence doesn't fit with their notions, they start to take extreme positions - for example, rejecting the very idea of categories.

This is, of course, absurd. Experience of everyday life makes it glaringly obvious that existence isn't one huge, undifferentiated lump!

Unfortunately, some categories may have grey or fuzzy edges and there may be exceptions and anomalies and this makes some people uncomfortable. It shouldn't though - it is just the way things are.

From a scientific viewpoint the existence of exceptions and anomalies is exciting and if enough of these pile up then the categories may have to be re-assigned (and no, Cap'n - this doesn't mean that I believe that the categories 'revival' and 'traditional', as applied to singers, are wrong! You've got a lot of work to do in order to convince me otherwise).