Stone types missing

I’ve noticed this before but it didn't bother me because i thought it was a “smart game design decision”, but i noticed things that to me had no logic that led me to compile a list of inconsistencies:

blocks that dont have:

• stairs
  - smooth stone
  - cut sandstone
  - cut red sandstone
  - endstone

• slabs
  - endstone

• walls
  - stone
  - smooth stone
  - polished granite
  - polished diorite
  - polished andesite
  - end stone
  - smooth sandstone
  - cut sandstone
  - smooth red sandstone
  - prismarine
  - prismarine bricks
  - dark prismarine
  - polished blackstone
  - purpur

• There is no smooth stone stairs

• Cut sandstone and cut red sandstone doesn’t have stair variant

• Tuff, Deepslate and Blackstone, and has the smooth/polished wall variant, while other stone blocks do not

• have that variant

• End stone doesn't have stone variants

• Only nether brick has a fence variant