Might as well eat somewhere nicer

Mostly correct. "Dehydrated" isn't the goal of par-frying first but some moisture is driven off. By just barely cooking them through at a lowish heat then freezing you can re-fry them at a much higher temperature to get a crisp exterior and hot, fluffy interior. Higher temp means the rate of water boiling out keeps oil from penetrating as quickly, but if you try that with fresh cuts the outside will burn well before the inside is ready.

For the record, the best fries are done with a seasoned batter before the final cook. Really get thay crispy layer and add a load of whatever flavor you like.