You could also argue that this was solved "along the way" and also not really clear back then. I am an AirBnB host myself and were also wondering about this recently and there are several factors today which contribute positively: Provided as a (technical) solution by AirBnB (Recommendations, IDs, etc.) but also how the internet/web evolved as a hole - A place that somehow manages that strangers meaningfully/safely interact with each other. This was never clear and also an uncertainty for Wikipedia (earlier) and now for AirBnB in a different and new way: Inviting strangers to your house.