If you want open software you need FOSS. Nvidia is not even close to FOSS. AMD is closer to FOSS.
Just because it's closed doesn't mean the driver is bad from a purely technical/functional point of view and for many people that might be enough. The parent sounded like Nvidia GPUs just don't work well under Linux, and from my experience that's just not the case. And the open AMD drivers took many years to get to the level they are now.
Technical issues with Nvidia I can think of are the EGLStreams with Wayland and Optimus.
I'm running the closed source Nvidia drivers and everything runs 100%. I can run most games as well.