Booking.com leaves hoteliers thousands of dollars out of pocket
theguardian.com
theguardian.com
I once had a travel agency "negotiate for me" a case where I had booked the wrong date, immediately noticed it and contacted back. The agency failed, so I called the hotel directly and they agreed immediately.
These services are usable as search engines perhaps but that's it. Never book through them.
It is not uncommon to call a hotel, say you want them to match booking.com rate and have them decline.
After that experience I decided that I will only go through platforms for smaller places, which is unfortunate. I'd much rather support them directly.