@chromeratt they just did that for their graph. Since there is a integer relationship between tbsp and tsp, it means its a direct relationship to tsp. But - for actually working in the kitchen, it's faster ( and this is the point of this - a easy way to get things done in the kitchen ).

Note that this is why measuring everything with a scale in the kitchen is shitty. It's a mind-numbingly slow way to get things done for people that have shit to do.