I list on VRBO as well as a number of other sites (Wimdu, Flipkey, GayBookings, Housetrip) and I've noticed this as well. I will get the exact same inquiry from a guest on airbnb, and then 20 minutes later on VRBO (for example) and the booking gets finalized on VRBO because of the payment terms as Olivier noted.
I pay for the listing on VRBO so I can do whatever I want with it, and I don't pay the 10% (but I paid $400 for the year). I can link to my own site, I can take payment directly, I can use VRBO's payment system, I can send links, etc. etc. So for me it's totally worth the $400 per year per listing, especially because I wait until Black Friday when they offer the subscription at 40% off (usually).
I am getting 0 inquiries from Wimdu lately, and I used to get half of my bookings from Wimdu. Now I get 50% from VRBO, 30% airbnb and 20% from the other sites. It's a pain in the neck to be managing all of these platforms, I wish I would get 100% of my bookings from Airbnb, but it's not happening.