Smart Guides are temporary snap‑to guides that appear when you create or manipulate objects or artboards. They help you align, edit, and transform objects or artboards relative to other objects, artboards, or both by snap-aligning and displaying X, Y location, and delta values., this is a very useful feature to create the great composition.
For example, smart guides helps you to position the object in the center of the canvas.
Or something like this.
For example, Photoshop, Illustrator, Gravit Designer and Figma (maybe something else) have a Smart Guides feature and it’s very helps to save the time, but this feature more appropriate for the design tool than to digital painting, but i think this very useful feature and it will be simplify the making of beautiful composition in Krita.