Then I know in Greece the booking.com commission is about 20%.... which is a lot! In Argentina it was (5 years ago) much lower due to availability of several other platform, so yes being the only provider is not a good thing
Btw I love booking.com: I still remember the scams in Venice until the internet popped up with reviews, and I really appreciate platform that helps who works very good: I met owners that told me: "yes, it costs, but I get customers as soon as I provide a great service"
I dislike airbnb as other have written: poor customers service when you tell them a host try to scam.