In my humble opinion, varieties are created by the design process, i.e. the decision to strike a coin from a selected pair of obverse and reverse designs. Any anomalies created by the minting (or striking) process are exactly that - anomalies, collectibility of which is in the eye of the beholder. The confusion was probably started by Freeman's decision to grant a variety number to the 1897 Dot penny. As I say, just my opinion. And the debate will probably go on forever. On my websites, I refer to variations to a particular "variety", such as variation in the date spacing, as a "sub-variety" whereas Gouby assigns specific identifiers.
You pays your money......................