I spent almost 10 years doing IT for a company whose backend was based entirely on as/400. If you've ever used a system like that, I'm sure you know where this is going... The console's that the front-desk or clerical users used every day had a steep learning curve. It was something that you would definitely not be able to walk up to and just intuit. However , once you figured it out, there is never going to be a fas…
Discoverability is another problem. You can have weird keyboard commands, but make it possible to find them without searching stack overflow. I miss when applications had a big bar at the top of all the commands you could do and their keyboard shortcuts. I'm on chrome right now, and copy and paste is hidden away in a menu. And the keyboard shortcut for it isn't mentioned. How do you think people learned the keyboard shortcut in the first place? Or apple phones have a bunch of gestures that are useful, but no one knows about because you can't discover them.