"Wholesale hotel inventory obviously goes back decades," said Cornell University School of Hotel Administration professor Christopher Anderson. "But what's happened as everything has moved to online marketplaces is that some of this wholesale inventory has leaked into the retail distribution channel. And that's created a huge mess for everyone."

"OTAs in general are the parity police," Anderson said. "If Expedia is controlling the inventory going out there and they see Firm A selling at a discount to retail, then they're going to have mechanisms to sort of catch that and police it. It becomes more straightforward for Marriott to control availability and rate."

Related: Marriott appoints Expedia to distribute wholesale rates