GPL has no requirements for author attribution which is contrary to the entire point of an MIT license.
That's why I described it as joining the Borg. You release individualism and freely give it to the collective. That's cool, and I get the ethos behind all that, but I don't want to add any of those constraints to my code. I just don't want credit for my work or the others to get lost. I don't think it's a hard ask.
Regardless, we ended up ultimately being a full replacement for the other project.