Because there are only four billion addresses all in all. Every device that wants to be reachable on the Internet needs one. These days, mobile devices don't ge

Because there are only four billion addresses all in all. Every device that wants to be reachable on the Internet needs one. These days, mobile devices don't get a public address anymore and there are all sorts of complications due to it. We're slowly transitioning to a new scheme with ample address space. But to nobody's surprise it's taking decades longer than envisioned.