Maybe it's just me but a note from the developer stating why it's important that some particular value be present is exactly the sort of help I would like when looking at a call stack that's dozens of levels deep. Especially considering that a panic terminates execution - I very much would like to know what was so critical that the program had to preemptively crash up front and not after pawing through code and docs.

I think it's pretty odd to use a quick example someone rattled off on a web forum to explain a function's behaviour as evidence of its usefulness or lack thereof, as if the only thing a person could possibly write in a freeform error message is "Our goose finder should always find a goose".