You are right
If the dog has loose undercoat you need to get most of that out before bathing. Also any tangles or matts need to come out because they will get worse after wetting. If there's a lot of coat packed in there, when you get it wet it basically becomes felt. You can either brush it out or use your blower to get it out before the bath.
With a malamute type coat, I doubt that it is long enough for the dryer to cause the tangles. Those are called whip knots, and if the ends of the hair starts folding in on itself as you are drying it can tangle. Then you need to back the dryer further away, and not flip it back and forth. My Samoyed girls that have a shorter working coat never had any problems with this, but a regular coated Samoyed would.
Oh, and your groomer surely had a dryer that was much much stronger than yours. A dryer so strong that it really can get out all that undercoat without brushing.