I went to the end of the world, attempted to get on my boat beyond world barriers twice and got kicked by probably NoCheat for "moving too fast". I then respawned about 100-ish blocks from the end of the world.
Well for one there is the border at 13500 that pushes even the staff back if they go too far. And for your information we use NoCheat because it catches any flying, nofall, or anything else that might send falsified move packets to the server. So technically it's necessary to keep order.