Why are African witches so superior to their European and US counterparts?

No. Actually you should blame the New Age (wicca) movement which changed, corrupted and watered down old witchcraft practices. Any sort of magic, religion, or witchcraft depends on the level of belief invested in it. Modern New Age witchcraft just does not inspire such belief. It's not even true witchcraft, but an amalgamation of practices and beliefs that have nothing to do with 'Old World' witchcraft. Not all witches are useless, by the way; just like not all christians are bigots. I have met powerful people from both of those groups that deserve much respect. Obviously, you have just not met the right people yet.