This is 100% a loophole and it is SO frustrating! When a guest disputes their charge, Airbnb cancels the booking, claiming that it is fraudulent. They do not dispute chargebacks, so the guest wins and the only person paying is the host. I am SO incredibly frustrated as this just happened to me and I have been attempting to work with Airbnb for 30 days now! I receive the same copy and pasted information from them over and over again.
To make matters worse, the guest who created the chargeback still has an active account AND is a host! There is literally no recourse. Therefore, any one of us can make a reservation, decide at the last minute we don't want to follow through, create a chargeback, receive a full refund and go on with 5 star reviews to do the same to someone else.
I even put together a huge file that Airbnb could forward to the credit card processor on my behalf. I literally did their work for them and no one would even think about helping me.
It is super frustrating and I am really sorry you're going through this! I am considering small claims or filing arbitration.