I suspect Airbnb wanted to do the Ryan Air business model, you have the base price and everything else is additional, the seat, the luggage, the logging in etc.
But it does not work out quite that way, the host bears the cost of any additional complimentary items they wish to provide.
The Airbnb pricing model and documentation is a dog’s dinner and presumably they like it that way, as it disguises a multitude of issues.