Originally Posted by
christianj
Straight off the Marriott Bonvoy FAQs:
What are blackout dates?
Blackout dates traditionally refer to a limited number of dates, such as during peak travel times throughout the year, when a hotel could choose not to have Members redeem Points for a Free Night Award stay. With our “No Blackout Dates” policy, Participating Properties/Brands have standard rooms available for redemption every day.
Blackout dates happened in the old Marriott world but were not all that common. IIRC someone in MR's central organization had to sign-off/approve any black out dates for a property.
MR mostly had inventory restrictions on redemptions, e.g. 30 rooms. If 30 rooms were booked for reward stays, the hotel was not required to offer more space if it was still selling rooms (unlike in the old SPG world).
The current high amounts of hotels displaying "Sorry this hotel is not taking reward redemptions at this time" may also be caused by IT mishandling by the properties.