I know Intel supports Linux via the upstreaming of Intel Linux drivers to the Linux Open Source Community:

Linux supported by Intel via the upstreamingof Intel Linux drivers to the Linux Open Source Community. Adoption into individual Linux distributions is dependent upon the OS vendor.

Am not sure how much AMD supports Linux, but have had problems with AMD processors when using Linux. That above pic is from a March 2018 Intel Sales Guide, and I know Intel has fully supported Linux for much longer than just 2 years. Michael Larabel has another interesting article – AMD vs. Intel Contributions To The Linux Kernel Over The Past Decade – that does an interesting comparison:

Driven by curiosity sake, here is a look at how the total number of AMD and Intel developers contributed to the upstream Linux kernel during the 2010s as well as the total number of commits each year from the respective hardware vendors.

Personally, I think AMD and many Linux Distros are just plain slow at providing and/or adding many product drivers, so it’s hard for me to find the actual blame. However, AMD even has problems getting updates to MoBo OEM’s, but Distros like MX Linux are also incredibly slow at adopting even the basic AMD processor drivers.

Looks like AMD had 3 decent years recently, but they still lag far behind Intel in providing Linux support:

If you’re building a computer, AMD based products require a lot more research, and then even more work making sure that all components are compatible … even then, it probably works right away with Windows 10, but only a few Linux Distros will have the right drivers if you’re using newer AMD products. Those Distros not working at first will eventually be updated (usually), but I don’t wait on any Distro.

Well, Intel clearly supports Linux a lot more that AMD does…