Earlier quoted context omitted.
This, unfortunately is not as true as I wish it was. I bought an RX 560 and tried to install Ubuntu 18.04. It could not propery drive my 4k display that uses DP 1.2 MST. That display has been working fine with a few different cards on Mac and Windows since 2014 when I bought it. I even tried the AMD pro drivers. Granted, the open source nvidia drivers couldn’t do it with a 1030 on 18.04 either, but the proprietary on…
I have no problems running my RX 580 with the amdgpu driver and recent versions of Mesa.. If I had to guess, Ubuntu 18.04 has some archaic versions of both the kernel and userspace drivers.
I tried the latest proprietary amdgpu-pro drivers also.
I even bought the RX 560 because some other Linux users assured me the AMD Linux drivers were excellent. My post here is to help other people so they can make a more informed choice in the future.