From a story-telling context, if all focus were on Wanda, I suppose it could make sense to keep DS out of it. However, considering the amount of raw power being used on a continuous basis, and considering the source of that raw power being the Scarlet Witch (a big deal, based on dialogue), it would be more logical to have DS show up to basically say, what the living hell is going on here?!? In fact, that amount of raw power should theoretically attract damn near every single capable magic user on the planet, possibly in nearby systems. Keeping it micro and unnoticed contradicted the amount of power that was being used. They honestly kind of painted themselves into a corner with that one.