The problem lies within the FAA itself and is certainly not meant to cover a DPE's lack of currency or skill.
This ^^^. Memory (perhaps flawed) says FAA policy requires that CFI check rides are supposedly done by FAA employees (and by DPE's only when specifically authorized by a FSDO on a case by case basis). Some of the CFI's I hang with do recurrent training for FAA Inspectors and generally report a surprising lack of proficiency. If all this is so, no wonder FAA doesnt want their staff doing touchdowns. (Not intended as a swipe at FAA folks, just recognition that FAA budget for recurrent training has been under pressure for some time.)