My wife and I make pot brownies all the time. As long as you know the dosage in your cannabutter you can deliberately choose how much to put in. If you make them the same way twice then by that point you know how big of a piece to cut to get a specific dose.
The other person is right when it comes to taking doses from edibles you get elsewhere with differing dosage amounts, or if you have poor self control or something, but edibles can totally be a primary way of ingestion, it's just harder to learn proper dosage than inhalation, for instance, you can easily make edibles too weak instead of too strong if you want to be careful, they're not always too strong and youre not always bound by God to eat too much, just be careful and not impulsive. You can always wait and eat more, you can't eat less.