Here is an example of how design sells a vision way before a product gets made.
Designers know that an idea is better than no idea.
A concept is better than idea.
A sketch is better than words.
A wireframe is better than sketch.
A prototype is better than a bunch of wireframes.
A finished, working product is better than a prototype.
So to get to the final intended state, one has to go through many phases.
Previous phase serves the purpose of promoting the next phase.
Flats and buildings sales process works through leveraging of visions, models and prototypes in this fashion.
In this case people see a model of a building.
It is there to represent the future state of the building.
It helps people visualise and understand how it will all look and feel.
At least to some extent.
The highest fidelity format serves the purpose to promote even higher fidelity format.
Final aim is to sell the full product via leveraging a model and/or a prototype.
This works all the time.
Even as far as big buildings.