Because that would result in 15 units of difficulty. The Task system is a way of having only 5 (6 in T4) discrete levels.
Task systems are a tool for faster and more cross-campaign similar play. A shorthand. To reproduce the same range at, say 2 point intervals, one winds up with 8 difficulties. 3 point difficulties gives 6 levels.
The labels are very descriptive of a Skill 1, total asset 2 character's chances.
I sometimes use half-levels... 2 point shifts... but have found that the descriptive power of the labels makes up for the reduced number of steps in play.
Task systems are a tool for faster and more cross-campaign similar play. A shorthand. To reproduce the same range at, say 2 point intervals, one winds up with 8 difficulties. 3 point difficulties gives 6 levels.
The labels are very descriptive of a Skill 1, total asset 2 character's chances.
I sometimes use half-levels... 2 point shifts... but have found that the descriptive power of the labels makes up for the reduced number of steps in play.