As other have noted your information is unfortunately out of date. Generally AMD GPUs work out of the box and Nvidia ones sometimes do not. And while Nvidia's proprietary driver is fine-ish, there were for a long time problems using Wayland compositors with Nvidia hardware. Hardware rendering was only enabled in the Steam client by default a months or two ago after Nvidia-related problems were addressed, too. And using Nvidia's driver taints your kernel prevents you from using Secure Boot, and other problems.
That said, support for Nvidia hardware isn't bad or anything. It's just that there can be little bugs and some limitations. And only Nvidia can fix them, and that can take a lot of arm twisting.