I wondered about the same thing, and the only thing that came up is that they might be reluctant to create new local boards because there are quite a few semi-active/dead ones so I guess they want to be absolutely sure that the same thing won't happen with new ones as well.

With that being said, I do think that Bangladash (and Pakistan) communities showed their consistency when it comes to activity and I don't think that same thing will happen with like with some other local boards. On the contrary, their numbers would probably grow like it happened with Nigerian board that is now one of the most active ones.