While Darktable has a lot of nice niche features, from UX point of view it’s 20 years behind any of commercial offerings. If GIMP is like open source Photoshop, then Darktable is like open source Lightroom - both GIMP and Darktable are absolutely crap when it comes to UX, unless you mastered them for 10 years. Darktable should focus on some UX/UI GSOC-like project and figure out their usability to be considered useful.