Because now, see, you need an army of very expensive lawyers to very carefully analyze the changes to determine if you can still be using the thing. The answer is always tricky, boils down to “it depends, now pls give us more of those sweet hourly fees and your own project description in detail so we may determine if maybe probably it’s ok in your particular case. Not guaranteed, of course, gotta have a court case to guarantee anything.”
So legally tricky, much legal busywork. Very courageous.