The heavy duty soaps used in dishwasher soap will strip the seasoned layer off your pans. Then you will need to re-season them. Some people like to make seasoning your pans into an extreme ritual that can be tedious. But if you’ve got stuff so hardcore stuck to your pan that a little soaking doesn’t solve the problem then your seasoned layer is screwed anyways. So you might as well let the dishwasher do the hard work for you.