Thanks for this extensive comment, David! I loved reading it.
What you say makes a lot of sense. It’s also exactly how I think about gathering requirements: Just like when you knew a product wouldn’t work for the clients, how can you gather requirements / test this hypothesis quickly?
Like you say, a prototype sounds ideal. Why couldn’t you build one earlier?
Or, to flip the question on it’s head, how can you ensure that people who are “convinced” about what they want, really want it? How can you codify this process into the gathering requirements stage?
I find these questions very interesting.