That's not quite true. They will usually allow you to continue your subscription if it run out not too long ago. But of course starting with the date it run out.
Also, there are some special offers from time to time, where you can save part of the price for a new license. But for a while keeping the subscription active has been the cheapest way to update (if you can call that "cheap"). And every time you have to remove "platinum support" from the order.
The one thing that has annoyed me the most, is that you need an active subscription to even download an install bugfixes.