Tell me the reason it is necessary for the project to create ANN on bitcointalk.
Although depending on different projects they have their own channels to discuss their issues privately, so I don't think it is an important issue.
I think they are not aware of the popularity of the forum. Even if the projects gets a lot of attention on social media and youtube, but why leave a platform like bitcointalk where they could get a lot of investors too ? I think someone needs to tell them about this platform so they can advertise here too. If they are still not interested, that does not effect the popularity of this forum.