The company doesn't want 65 hour lines in most cases. That is very unproductive. Keeping in mind that DL does a lot of different types of ops (high cycle domestic as well as long haul international including 12 day trips, etc) there has to be a low guarantee as a catch all. It also helps serve as a small accumulator to potentially mitigate furloughs, downgrades and lineholders getting bumped to reserve during lean times.

There are very few pilots at DL unwillingly only getting 65 hours of pay. A much higher priority is continuing to raise average daily credit/min day and vacation credit. The company always has incentive to fly the vast majority of its pilots higher than 65 hours a month credit so that problem will, as it always does, take care of itself.