To locate urself by sync 2D->3D spaces, this avoid to make twice the work cause you skip steps as you can start painting in a blank canvas if you wish or over UV template with no guides and you still know exactly what part of the mesh are you going to paint even before you paint, specially useful in messy UVs or even UDIMs - with several UV maps -.
As said this is for a handpainted workflow, so not PBR, not shaders, etc. That’s why using Krita for it can really make it powerful as Blender don’t have proper workflows, tools and good UI/UX for it yet, so having something nearest to the idea of a live link between Blender and Krita would be awesome.