@Laura2714 I'm sure there are some exceptions to the rule out there, but honestly I don't think Airbnb is the right platform for what this guest is looking for. He could use the search filters to find "Shared Room" listings, as they are the closest you can get to the hostel experience, but in all likelihood the results will just be a mix of a) bare-bones legal hostels, b) terrible illegal hostels that are just bunk beds crammed into residential flats in popular cities like Paris, and c) the living room sofa of a host who lives alone, and might be awesome company, but who doesn't have access to a pool or a campfire.
There's an economy of scale involved with doing those cool hostels with a fun social vibe - you really need a full-time staff looking after those campfires and pools, 24-hour security, and vastly more liability insurance than "AirCover" against all that can go horribly wrong. Airbnb's listing management software is not nearly sophisticated enough to fit the needs of a really good hostel, and its service fee structure can't possibly compete with the more established hostel booking platforms like Hostelz and HostelBooker. These awesome places your guest visited are not listing on Airbnb for a reason.
One "category" that I think would be great on Airbnb is something like "Social Stays," in which a booking organically includes some interactive experiences. I pitched the idea directly to Brian the one time we met. I could tell it was never going to happen.