I'm not a lawyer, but I'm pretty certain that's not how the GPL works. It has no effect on the content you create using the tool. It places restrictions on redistribution of the code itself. I don't think there are any limits on what you do with gimp or blender, unless you are modifying its code and redistributing it.
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/
That is correct, but there are plenty of lawyers who interpret things incredibly overly-conservatively to save their own ass, just in case.
If you're a senior enough manager and have a legitimate business reason then you can often push back enough and get them to give in, but it's really a question of whether it's worth your time and effort internally.
Of course - the GPL thing is just FUD. The company I work for (Red Hat) sells tons of GPL software to small and large companies, including huge media/entertainment companies, and none of them is talking about how the GPL is "radioactive".
Because libc is licensed under LGPL and not GPL. GPL in and of itself isn't bad if you're not developing code that links it in. LGPL is also widely used in the CG industry (Qt etc...). If Blender licensed their API under different terms it would greatly open things up.
The current version of GPL is 100% toxic at many places I know of - this is not overly conservative lawyers - you have all sorts of rules around releasing your encryption keys - secure boot chains etc - it’s a no go and viral
A friend worked at a company where they banned GIMP as they feared that editing logos and other trademarks in it could invalidate them.
Even working for a tech company, I don't think I would suggest using anything GPL as it would cause a fuss.