Just used that ratio looking at the 5 default vendors, 4 accept only Crucible Marks and 1 accept Vanguard Marks to purchase regular legendary items.
Since all of these vendors sell basically PvE items and PvP items do not exist, why force us to use PvP marks?
You seriously cannot think most of the nerfs and direction of patches hasn't been way more leveled towards the PvP complaints can you?