Why Promotion is only in Erangle and Livik?

I know promotion is very hard and complex, But I am starting to manage it, little by little, I can get through promotion matches easily now. but one last complaint. Why I cannot play other maps? Why I can start a promotion on erang or Liv only? And yeah. To be honest I only play erangle because there's many possible rotations and your not going to get stuck in the zone easily. In Livik to be honest I don't like how fast everything goes in that map. First of all, Iam just busy looting in a building, I get out and instantly I get shot out of nowhere with 40 + players still remaining. Secondly, It's the only map where I don't hotdrop, Why? Too many dead zones and Trap prone areas. Especially at power plant. Thirdly, Campers are clustered at the end. So it's a gamble. If the zone is in the side of you or not... Hope in the future we were finally able to play other maps during promoting...