Because is getting resources and screen time from the main game (20 years old and pretty popular, remember it? It's called Infinity) It's CBs main product, but it's being promoted close to zero.
Well news could be next week but they are cutting it pretty close. With something like a premier of a new set you want to give people a good amount of time to know about it before it's on sale.
Mounthaven preorder opens Tuesday, having news on an Adepticon product for Infinity the week after gives two weeks before the event, with a preorder perhaps to run from the first day of Adepticon and then for 2-3 weeks.
It could be an attempt to not have conflicting promotions between Infinity and Warcrow. I thought we'd see at least one more video on Mounthaven though. Probably next week.