Porgress isn't meaningless in the proposed changes as it still severely impacts the ease and speed of clearance of all duties within the same tier. For instance, current vanilla endgame dungeons ran at BiS gear are not even comparable in terms of efficiency comparatively to what they were with vanilla gear.

It just stops doing it for older tiers comparatively (but not quite either because the higher ilvl gear gets, the more it fills the substats when synced anyway so there is still some mild gear creep involved).