There's also the implication that there are different types of magic. The whole reason Strange goes to see Wanda is that he (or Wong?) identifies the runes binding the demons pursuing America as witchcraft and not sorcery. If they don't vibe well with one another, that's a good reason why the sorcerers didn't catch on to what was going on in Westview – particularly since it was just post-blip, and many of them were probably busy putting their lives back together.