Earlier quoted context omitted.
Where would the idea be assigned if it doesn't know who the user is?
The idea is to fake the UX without storing anything permanently. Generate a temporary ID to store data to while the user is playing with the site. If they've added ideas they want to save permanently, overwrite the temporary ID with the new user ID. Storing the data only matters if they sign up. I'm a programming noob myself, but I think this should work. If I'm dead wrong, it should only take a couple minutes for me…
I understand now... I don't think I would go that detailed as they have, though. I think I could achieve something similar with a demo made with Javascript on the landing page, no?