It's coming from technical ignorance. There's little wrong with FUTOs license, here are the limitations:

First the good:

You may use or modify the software only for non-commercial purposes such as personal use for research, experiment, and testing for the benefit of public knowledge, personal study, private entertainment, hobby projects, amateur pursuits, or religious observance, all without any anticipated commercial application. You may distribute the software or provide it to others only if you do so free of charge for non-commercial purposes.

Yes, good, I don't want Google using my code to make billions.

And the not so good:

Notwithstanding the above, you may not remove or obscure any functionality in the software related to payment to the Licensor in any copy you distribute to others. You may not alter, remove, or obscure any licensing, copyright, or other notices of the Licensor in the software. Any use of the Licensor’s trademarks is subject to applicable law.

Bad. If I forked and majorly modified the code by significant contribution, I don't see why my release should have a "donate" link to the original producer and not for my efforts the donor is actually using. This is the same problem the first limitation seeks to address, but from a different angle; namely: monetizing "intellectual property" instead of work.

Copyleft is cool because it means freedom, but everyone in here fighting because code first prevents them from potentially monetizing the projects they like is completely missing the point of copyleft.

If you ask them to articulate their concern, I haven't heard one that isn't on the lines of "I want to be able to use this code in my paid product"...