Is because government after government refuses to allow it to grow. The demand exists but the available housing doesn't. So what we have here is all of these leftists claiming that it's just a few Jews living in Hebron that need to be protected (as if the leftists don't, the northern and southern borders don't, etc...), when in fact, if the Hebron community would be allowed to grow naturally, then it would be a LOT more secure. THAT is hypocrisy.
Yemen's Houthi rebels commit to peace plan in letter to UN chief, BBC reports (Haaretz)
from the article: Hypocrisy in Hebron