Yes of course any government has this power to not allow any kind of industries, business or even people to enter in their jurisdictions. If I am not mistaken the most popular country that ban bitcoin is the china then many more countries follows. Well they have their different reasons why did they ban bitcoin in their land and we cannot do anything about it because that is their choice and decision. Somehow we are still hopping that their decision will change. Just imagine that if they will change their mind it is just like an additional users for bitcoin. And we all know that additional users will come up with additional investments and demand then the value will increase again.