Because sending a light beam 10 miles away is slower than not doing so, obviously. Light isn't instantaneous in this universe.
It's surprising people still don't get this. Operating a computer miles away will always be slower than operating a computer centimetres away. You can be smart about it and optimise as much as possible, but Google isn't running alien tech that magically is orders of magnitude better than consumer hardware so that it overcomes the distance issue.
Light takes about a millisecond to travel 200 miles. Compared to the latency introduced by computation, it is pretty insignificant, unless you are connected to a server very far away.
