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.
"More people would learn from their mistakes if they weren't so busy denying them." - Harold J. Smith.