My thinly-veiled lack of understanding of Linux is in shambles. CPU optional?

I appreciate the informative reply!

I personally have not moved to Linux as my daily juuuust yet, so I’m relatively uninformed, but I am curious. What were these “proprietary” versions the article mentions before the open source ones that it’s comparing against? Were they also Nvidia released, just closed source, or would those be from OEMs (Dell, Lenovo, etc) who include Nvidia hardware in their laptops/desktops that are shipping with Linux installed by default?