It’s because of the anisotropy. Suppose the universe was a regular grid of voxels. You could run experiments to prove that. I don’t understand the details, but

It’s because of the anisotropy. Suppose the universe was a regular grid of voxels. You could run experiments to prove that. I don’t understand the details, but that was Feynman’s counter argument. (See the “messenger lectures” series on YouTube.) If the grid isn’t regular, you run into other problems. But iirc at one point Feynman was toying with the idea that the grid might be randomly distributed.