warby: I think his friend means that if you're using texture atlassing as well as wanting tiling textures, the only way to achieve it is by using more polygons. Imagine a quad that had a texture tiled in 4x2 grid. To do that with an atlassed texture, you'd need to cut the quad into 8 separate quads and UV each of the tiles…
If you have many objects in your environment use one texture, you'll end up with good speed results. There are two good reasons that engines often support one/more of: batching and instancing. State changes are what happens when you change which shader you're using or which texture the shader uses, or a bunch of other…