I experienced this on a late oversold flight from DTW to MSP. The GA chose to board FC - then the rear of the airplane - then Elite. Frustrating
I just went on when they called the folks in the rear of the airplane even though I was in a preferred seat. I do not find them to be very tight on checking in DTW when you have status - the same can not be said for DL.
I agree with you, elite preboard is a key perk.