For years, the deposit was actually taken, sometimes over long periods, and an ongoing claim would hold it in airbnb’s coffers. It’s not in Airbnb’s interest not to actually take it, but in a way it is:
guests with no big allowance on their card, could not make new bookings , before the miney was back.
A cancellation shortly before checkin (even a host cancellation) woul block their card by the withdrawal of the deposit and they would be stranded woth no way to book elsewhere with the same card.
The service rvolved from long holidays to successions of short stays. Even a rich traveller on a crosscountry or cross continent tril would find all his cards maxed out with short time. Banks take their own good time to credit funds back. That the money was sent back, does not mean, that the money is available- there may be a long weekend and two days of validity between return and availability.
It’s in our interest, that the money is not taken, but airbnb only gets a claim to withdraw at need. What could be imporoved is clarity over the procedure and less arbitrary decisions. But these would happen with the miney on airbnb’s bank account as well.