Yes the GPL doesn't apply to work created by GPL software. I've heard people in companies be worried about it though because they misunderstand "using GPL libraries" as applying to work created as a product of them, rather than strictly software.
The Blender Foundation is quite upfront about this though to prevent misunderstandings. It's directly addressed on the page that explains the license: https://www.blender.org/about/license/
The case in point here though was GIMP not Blender. I'm not sure whether they provide or provided such clarification.