(Disclaimer - this happened before 'Corona-Rona'., or whatever they want to call it nowadays)
I am quite the fan of Airbnb really in many respects, but with one notable exception; the capricious application of their EC policy is my main beef. An interesting example of how absurd it could be capriciously applied.
Two people book my place, I hold the time slot for 1.5 years, at a time when I am booked solid 1.5 years ahead. Three months before coming they add a second couple, cool. A mere month before coming they add a 3rd couple, but soon right after I get a message from Airbnb that the reservation has been cancelled with full refund for all because one person in the 3rd couple recently added can't make it, because she needs a knee operation. What a coincidence, or how slick. They send the 'medical proof' to back their claim and the lazy whomever at Airbnb that handled the case did their thing without further thought.
To be fair, in the past Airbnb always has consulted me first in any and all cancellations, and always have given me the opportunity to 'help' with the logic of the situation and work something out with the guest to everyone's satisfaction. Not this time. In essence, the adding of a 'third party', after the fact, gave license to the whole group getting out of the reservation and be fully refunded.
From that day forward, I started thinking in a whole new way how to play the game. All events do have an object lesson.