I'm not sure the low response in 4b is just a matter of purposeful neglect. I post there sometimes but I prefer general and 4a because of the fast pace and I find more threads created there that peak my interest to incline me to chime in. And 4a for me isn't just a "hair" thing. It is kind of a water cooler spot. As mentioned, 4a and general have always been very open to whomever wanted to ask a question. It's not like since a person is type x they have to post their question in type x. I admit I don't visit 2, or the 3abc that much so I'm not sure of the vibe there but most regulars in 4a could not care less about hair type.
A black woman's fro is worth a million words- adthomas