That would violate the Cosmological principle - the idea that viewed on a sufficiently large scale, the properties of the universe are the same for all observer

That would violate the Cosmological principle - the idea that viewed on a sufficiently large scale, the properties of the universe are the same for all observers. Also the Copernican principle - the idea that our observation point in the universe is pretty average and not overly special. Of course both of these principles aren't strongly supported by evidence. They are still usually assumed because they keep cosmology sane and verifiable.