True, European empires pioneered human sacrifice on a broader scale than ever before, putting even the Aztecs to shame.
It is hardly surprising that in the brutalized, divided and hateful conditions in which people are forced to live (In Africa and around the world), ancient knowledge (or the remnants thereof) is sometimes used in brutal, divisive and hateful ways. Much as "modern scientific" knowledge is used. Science is not "good" or "bad" because someone uses it for "good" or "bad" purposes.
Then again there will always be con artists who have a different ancient knowledge, the knowledge of peoples' desperate hopes and self-deluding gullibility, quite apart from any other ancient knowledge that they may or may not possess. There is nothing particularly African, Caribbean, or Obeah-associated about these types of people; they are the same type of people who send people emails advertising creams which will make their penises bigger.
Nor is it surprising that in desperately deprived communities, individuals can be used as scapegoats to vent their frustrations (or people can be deliberately made into scapegoats for ulterior motives).
If you define witchcraft in a negative way, the white western world system is certainly the biggest witch out there at the moment. Most of the churches are definitely witches as well. At least the conwoman in Zimbabwe who got a wealthy client to pay her exorbitant sums of money to import mermaids from the UK to track down the clients' stolen vehicle, had a creative imagination and swindled someone who could afford to be swindled. The churches preaching "prosperity gospel" and all this BS don't even write their own script, and they're swindling people who can barely afford to eat.