The head writer of WandaVision described Strange's magic as "more of a masculine magic not at all aligned with Salem and our sort of Americanized version and feminized version of witches and magic.”
Of course Wanda isn't American (though she's played by an American) and Strange is (though he's not payed by an American), but all the other witches we saw in the show were from Salem, Mass., so I get where she's coming from.