Let's do some simple math!
The current rate that Airbnb charges guests is over 15%!!!
So let's do some simple math. If you are charging $200 per night on a 5 night booking Airbnb is then charging the guest $150. That is money you could be using. Using to attract customers and/or increase your profits.
You could spend $50 in advertising to acquire a new customer, offer them a 5% savings, and still be collecting $50 more profit! Now multiple that by say 50, what do you get?
An advertising budget of $2,500
Customer savings of $2,500
Increase profits of $2,500
Yes, this is simple math and there is some cost in having your own booking solution, but I hope you can see where this path is leading!