The various dialog boxes and widgets in apps like Gimp and Inkscape always seem fussy and annoying to me, especially when I know exactly what I want. If I could talk to the app, I would say "put margins 2cm from the page edge" or "position object X halfway between objects Y and Z", etc.
Blender has a Python console, and it's even somewhat discoverable because you can find out how to script an action you do in the UI, but the Python API is too verbose and ugly to be an actual daily mode of operation, I think.
Oh, you don't?
All of the software you mention has had, over the versions, introductions of major bugs, regressions, UI elements changing for the sake of it, features available in a previous version being removed in a subsequent version (sometimes to be reintroduced later)...
Is that your definition of utterly reliable and predictable?
Well now I'm really curious about your actual software use-cases here. Because regardless of whatever "end user not dev" use-case I can think of, out of the many multiple dozens that instantly spring to mind, I cannot name a single one that has not had for 1-2 decades multiple well-known, widely-used-daily, best-in-class apps or suites on the market that are fully GUI-no-CLI and are at the very least evidently "reliable enough". Whatever GUI app I have used in the past 10 years, we can talk GIMP/Paint/VS/Sublime/VLC/Photoshop/Lighttable/LuminanceHDR/Blender/Unity/Unreal/VScode/Thunderbird/Firefox/Chromium/archival-tools/file-explorers/countless-others --- not only have they been utterly reliable and predictably delivered as was demandedd, their CLI alternatives hovered between non-existent and underfeatured.
So "end user not a dev" to me sounds like you must be a sys-admin or maybe, "author of man pages" ;)