New update brought several restrictions, thus raising the market value of oil.
Restricting the player to certain battle grounds.
It will increase focus on particular battles, and player can be ranked according to loot leaderboard. It also restrict the appearance into multiple battle grounds at the same time.
They also introduced the box's, for which you can travel and collect it with certain items in that box.
This is being realistic structural constraints that present in war and it is better to have oil company now and control the dynamics of war.