The use case is that you can pass a texture atlas to your shader and sample from it without artefacts.
I’m making a voxel game and I want to pass a texture atlas (imagine something like this but in the right shape) to my shader so that I can use 1 mesh and 1 material per chunk instead of N meshes and M materials.
Currently I’m using texture arrays but there are significant issues compared to proper array textures, e.g. if I turn on mipmaps I get seaming, and also there are limits on the number of textures. The alternative hack is to use a single 2D non-array texture but this also has issues with artefacts because now there is just 1 sampler and it doesn’t understand the layout of the atlas.
I found another thread here on PBR texture splatting where they discuss using array textures for splatting terrain.