I've wondered about that myself as well as recommendations from some about backing off the plug from snug, I'd think that would cause the threads to stretch prematurely as well. I'm guessing the speed style is to get people to remove and clean them more often in an attempt to address the stuck plug complaint. I'd also think any leakage into the unthreaded areas might force crud into the threads more when removing it, possibly causing a lapping effect/wear on them.