@davidaugust I'm a UI/UX designer and I'd like to also add that it depends on the target demographic of the interface as well.
If you're making an advanced/technical tool, it's ok if the UX has to be explained to someone who's never used anything like it before, because your target demographic for designing the tool is already familiar with the UI conventions of that particular niche.
There's a balance between featurefulness and discoverability that can and has to be struck for each individual project.
Just saying this because some people think every UI has to be simple and minimalistic at the expense of usefulness, while others think that every UI has to be advanced and complicated at the expense of usability.
@hazelnot @davidaugust also, there's a while host of machinery and programs in a literal "the person using this must undergo training" context.