Yes. But how do you propose a city planner selects the right people to talk to about urban planning? The "users" (citizens) would first need to educate themsel

Yes. But how do you propose a city planner selects the right people to talk to about urban planning? The "users" (citizens) would first need to educate themselves on what's being proposed and what impacts it might have. They also might not be representative of the demographic actually being most affected. Maybe they just don't care. By leaving it to citizens to self-select, you get the people who are motivated and at least marginally more educated on the issue than some random Joe off the street.