These PRS shooters think the 6mmARC has a competative advantage over the 6.5 Creedmoor and 6mm Creedmore past 600-700 yards primarily due to less recoil and being better able to spot your own misses so you can make a quick correction for a follow up shot in competition (generally 2 shots per target). No advantage for the first shot which is all that matters for hunting.

The primary selling point of the 6mmARC is that it fits in an AR 15 for medium range hunting and 1000 range performance on paper/steel. But PRS shooters (all shooters) are seriously disadvantaged with an AR at distance.
Aim small miss small.