" wonder why that would be? Lower manufacturing cost to install a sealed unit vs sticking a piece of cork (or suitable substitute) to the frame? "
Seems to me that you don't know what are you talking about
Before Danielsson split with Loop HD reels cost around $700.
Tibor reels for example are offer to shops and guides ( trust me…..) at 40 -45% discount.
Since Danielsson sells its reel directly ( no Loop middle man ) we can all buy for what fly shops or guides used to pay.
The drag system is sealed and based on multiple carbon and steel discs ( similar material used in formula 1 cars).
Look at HD, FW or LW disck and you will know what I am talking about!
No hydroplaning effect.
http://www.danielsson-flyreels.se/us/bromsteknik.php
see pictures
The drag works smoothly in all situations, regardless of high or low temperature, without changing brake torque.
To design a drag that maintains the chosen torque setting, the drag material cannot be flexible. (If the dimension changes with temperature etc., the torque will be changed). Neither can the drag be lubricated, since lubrication introduces inevitable friction changes as temperature, load and rotation speed change. Cork was therefore completely inconceivable.
Our experiments led to a
carbon composite, stable up to 2000° C and extremely wear resistant. The advantages of this choice are obvious: the brake torque stays invariable independent of rotation speed and temperature. This decreases the risk of breaking a leader, fatigues the fish faster and gives you better control so you can concentrate on the fish and not on adjusting the drag.
It's impossible to design a good drag system without sealing it. Reels with drag systems that aren’t properly sealed can be used in dry conditions, but when the drag comes in contact with water the friction changes dramatically. Water planing can be the result and with that you lose control of the fish. Since Danielsson reels are completely sealed they still maintain all their functional qualities when wet.