For traditional grinding, which most makers are familiar with, there is the problem of too many points. By rolling the bevel on the cutting edge the sharpener will reduce the points by two. Another factor which affects the cutting, chopping or slashing of a knife is the height of the bevel. The shorter the bevel is, the more of a wedging effect will be produced when cutting. Short bevels are ideal for knives that are designed for heavy work.
Higher bevels are more suitable for knives that are designed for smoother cutting.
This is due to the different angles produced ranging from shallow to steep. The steeper angle will perform better for slashing and fine cuts. This is within the same concept that the height of the bevel. It is all a game of angles when it comes to determining what edge is needed for a particular knife.