If you can't use a library because it's GPLv3, then the company would need to invest some time and money into reimplementing the features they want. Guess who gets more paid work?
Depends on the constraints. You might not get to build that proper reimplementation and instead get stuck with quickly duct taping together a rough approximation that never gets the requisite time and resources to make it good, whereafter it becomes a persistent thorn in your side until you change jobs.
