The main target of the Godot Engine are game developers. But Godot's easy workflow and functional UI elements, makes it also a good fit for non-game applications. There are already some out there you may know, like Pixelorama, an Open Source 2D sprite editor.
Most UI frameworks are already graphically accelerated. But as stated above do the absolute minimum when updating the screen.
You don't need to redraw a static label 60 times a second.
They have totally different use cases and are written very differently.
Games use as many resources as they can to get maximum performance for rendering. This is not desirable in an application.
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I mentioned above but Godot has a low processor mode that gives you some control over the refresh cycle when nothing is happening. I doubt this completely alleviates the problem but I think it's worth profiling it for individual use cases.
It's still the same essential issue. You only want to draw what has changed and only when it has changed.
Lowering the rate could make things look worse when they actually do update and cause unneeded redraws when they don't.
I get not wanting to learn something else. But it's a case of using the right tool for the job imo.