The relevant "derived work" definition for the purpose of linking isn't one stemming from copyright law, it's the one in the GPL itself. This is because the GPL defines what licensees are permitted to do with the licensed work, and it imposes restrictions on those rights. Copyright law by default lets you make very little use of the software - the GPL broadens that out to include various forms of use, if (and only if) "derived works" fall within its scope.
You could ignore the GPL and static-link a piece of software to a GPLed library, but if you did so, you'd legally need a different right to use the GPLed library, because you hadn't complied with its license terms and so only have your minimal rights to use someone else's intellectual property.
Said differently, the GPL doesn't try to apply itself to "derived works" because of some contralegal dictum they don't have a different creative origin. It merely says "you have two choices - license the things you link with OUR stuff under OUR terms, or you don't have the right to use our stuff".
The relevant "derived work" definition for the purpose of linking isn't one stemming from copyright law, it's the one in the GPL itself. This is because the GPL defines what licensees are permitted to do with the licensed work, and it imposes restrictions on those rights. Copyright law by default lets you make very little use of the software - the GPL broadens that out to include various forms of use, if (and only if) "derived works" fall within its scope.
You could ignore the GPL and static-link a piece of software to a GPLed library, but if you did so, you'd legally need a different right to use the GPLed library, because you hadn't complied with its license terms and so only have your minimal rights to use someone else's intellectual property.
Said differently, the GPL doesn't try to apply itself to "derived works" because of some contralegal dictum they don't have a different creative origin. It merely says "you have two choices - license the things you link with OUR stuff under OUR terms, or you don't have the right to use our stuff".