I haven't followed the creation and growth of that community at all, @Gilles, but maybe it's a little bit too soon for that community to take off, given that, e.g., even this community isn't still that great.

@nbro I tend to agree that a site about teaching CS is overly specialized‌​, but they met the requirements for starting an SE site, so there it is

From my perspective, on this website, there are maybe, at most, a full hand of people that have a certain level of expertise in CS and that regularly participate in the community's growth.