This level of high-end audiophile mastering really is a less is more thing. They are in reality little more than flat master tape copies done through the best kit audiophile money can buy, i.e. Grundman, Hoffman, Gray etc are doing very little if anything EQ or compression-wise, just bringing the kit, care and experience. This being why some of us feel they can on occasion lose the artistic intent of say an original RVG cut where I’d argue the horns being right in your face was a very deliberate artistic decision.
As I’ve said before I suspect RVG deliberately recorded a bit bright knowing he’d cut treble on the cut, i.e. a kind of DIY noise reduction. I think this is why some Japanese pressings, Tone Poets etc can sound a bit accentuated in the drum kit metalwork to my ears. I don’t think it is deaf mastering engineers, just maybe a misunderstanding of original artistic intent.
I also think the engineers I mention are all way too good to only trust their ears, as you say it will be a multi-person team and in reality the buck likely stops with the recording’s rights owner. The problem comes with clearly deaf rock stars who do usually make a horrific mess remastering their back catalogue.
PS Given Kevin Gray seems able to knock out about 10 albums a week I suspect it is a pretty simple process, albeit one done at a very high kit and QC level.