Some might say that, but it's never been true; it's always been fine to make changes to a GPL program for personal use, without even telling anyone you did, muc

Some might say that, but it's never been true; it's always been fine to make changes to a GPL program for personal use, without even telling anyone you did, much less tracking down the original author to give the changes to them. The spirit of GPLv2 is "I give you this source code, if you give it, or a modified version of it, to anyone, you have to (perhaps also) give it to them in a form they can actually use.".