He missed one very important point: Grinding is not fun, by definition. Grinding, whenever it is used by the gaming community, is used to describe something they do not enjoy. This is why people do not always agree as to what constitutes grinding, because different people like different things. Grinding is repetition in a game (usually forced by some aspect of gameplay, whether it's a certain reward or simply to progress the story) that a player does not enjoy. Repetition alone does not make something a grind. That's why no one ever talked about the grind in Tetris, despite it being infinite repetition.