The European Hotel and Recreation Association started a direct booking campaign a while ago.
This to reduce the influence of Booking, Expedia, HRS and in lesser degree AirBnB.
This could also help AirBnB hosts that also take direct bookings. Take a look at their website: https://www.book-direct-shop.eu/en/
This checklist is also very interesting for hosts to help increase direct bookings: https://checklist.book-direct-shop.eu/index.php?lang=en
This is some interesting background information on how the big hotel chains benefit from direct bookings, but this is also valid for smaller businesses and private rentals.
https://skift.com/2017/11/01/hotel-direct-booking-pushes-really-worked-and-owners-were-big-winners/