The problem is with GPUs. The game already has a lot of draw calls (the fewer the better). So say you have a wall with 1 mesh with four draw calls you have say, 20 posts in that wall and you make a prop for each one of them you'll have 20 * 4 = 80 draw calls instead of 4. Two walls 160 instead of 8. There are probably ways to optimize this, but currently we do not have such code.
EDIT: Textures don't affect drawcalls it seems.