DSLR cameras, by and large, give very complete information about how the photo is exposed, in the form of a histogram and image of a trial exposure. It shows the light distribution for both luminance and the colours. It shows if there is any clipping of highlights and shadows. Looking at the test image itself allows me to quickly assess whether the key tones are correctly exposed. And if they are not they will be close enough that I can easily correct them in post processing. 

This seems to me to give all the information I need to make an accurate exposure. In fact I can't imagine a better way. And yet many people still advocate using the Zone System. But I fail to see it's advantages. 

There was recently a similar question: [Is the Zone System useful with a DSLR?](https://photo.stackexchange.com/questions/867/is-the-zone-system-useful-with-a-dslr). While it gave some interesting references the replies were bland statements of the form 'it is worth it'. 

So I am posing the question in a more direct and specific form in the hope I will get more specific answers: 

Why should I use the Zone System when the test histogram and image seems to give me all the information I need?