Why does it matter that there has never been an independent Palestine in the past?

One thing that opponents of Palestinian independence seem to mention fairly often is that there has never been an independent state called Palestine at any point in history. That is true, but who says it matters? Prior to 2008, there was never a nation named Kosovo, but now there is. The original thirteen US states were never fully independent prior to 1776. Similarly, Canada was never fully independent until the British Parliament ped the Canada Act of 1982.