If you're asking why can't you just preset the amounts for all recipes to be the same, well you could be using the "default amounts" in your ingredients, but it's not that simple as every recipe has different grains and water amounts, so the water profile calculation will be different for different recipes and for different volumes, efficiencies, and batch sizes.
Some other competitor software does offer "ez buttons" to tell you what amounts to add to hit your target profiles, but in general they're not very accurate and will offer counterproductive additions that don't work in reality, like simultaneously adding chalk to lower the pH and hit your "hardness target" (but chalk isn't very water soluble and you should never be targeting a specific alkalinity or hardness), and also adding baking soda and then lactic acid as well.
We're working on adding a more useful friendly solution while also taking these errors into account, in the mean time it's really just a "hunt and peck" workflow to change the amounts by hand until you're happy with the results