A generated image can be technically clean and still feel unfinished. Surfaces become too even, highlights too polite and the whole frame begins to carry the same perfect digital texture.
Grain should respond to the image
Authenticity Grain gives you control over size, chroma and highlight response, so texture can belong to the frame instead of sitting on top of it. A quiet portrait and a large campaign crop should not receive the same treatment.
The controls stay local and visible beside the rest of the workflow. You can judge the finish while the crop, color and enlargement decisions that shaped it are still in view.
The final decision remains part of the system
Because grain is another connected step, it can be changed, compared or removed without rebuilding the image that came before it. The finish remains a decision, not a destructive filter.
Texture should complete the image, not cover it.