> when I see people using something in a way it wasn’t intended (...), my question is: how is this UI failing them?

This is a legitimate question, but not the only one in that situation. Another view, more in line with the unix philosophy, is that "using something in the intended way" is a meaningless concept. A tool must work always, no matter how it is used and abused.

Thus, instead of asking "how is this UI failing them?", you could be more pragmatic and ask "how can I optimize the UI so that this usage works correctly?"