Facebook was not first to market. Deep links have been around for a while. Also, it looks like URX isn't on the supply side (they aren't providing ad inventory, instead leveraging mobile display networks - so Facebook isn't competing with them directly), instead focusing on the demand side and providing robust analytics and targeting. There is no reason why they wouldn't be able to include Facebook deep link ads to their customers. Also, there is a pretty large section of the mobile web that Facebook deep links won't cover.