A long, long time ago we decided that all textures would be conceptually "multisample" and some usages would simply require sampleCount=1. This seems to be what Vulkan has done. However, Metal doesn't make this decision and has MTLTextureType2D and MTLTextureType2DMultisample.

This becomes a problem with argument buffers because they also distinguish the two types. I haven't looked at argument buffers closely but @kvark says you can't just take a 2d texture and put it in a 2d-multisample argument buffer slot.

In particular, in bind group layouts, this means you can't bind a texture with sampleCount=1 to a "multisampled-texture" binding point. This really seems like something that should be possible. But with the constraints of Metal (and possibly D3D12?), it seems necessary for texture creation to distinguish non-multisample textures from single-sampled-multisample textures.