There are two major hotel OTAs which allow earning of airline points for hotel bookings, PointsHound and RocketMiles. Up until today United was partners with both of them. Apparently UA has entered into a strategic relationship with RocketMiles and made them the exclusive partner in that market. As such, PointsHound is no longer able to grant UA miles for new reservations. Less competition is rarely a good thing for customers; we'll see how this one plays out.