[gibolt]

The difference here is that those parties are approximately the same every time, minus different people.

Every room from every provider is different. While you can only go to one once, a metro area could have 100+ rooms. Quality varies, but the most motivated people could go regularly and not run out.

The tiny number of people who can go through a single room at a time limits scalability/profitability, while also ensuring most people in a local area could still be first-time visitors.