@Miriam321 As far as I can see Airbnb's only reason for continually extending the date for cancellations is to manage their cash flows. As a result it just means hosts calendars are blocked until much nearer the date and hence its unlikely that the dates can get rebooked.
Perhaps Airbnb could do a little sum that will show that this policy is actually damaging them as well given that the refunded money will not be replaced and hence their income will end up down overall compared to what it would be if they just allowed a time-limited cancellation for all bookings this year.