FTFY
Seriously, though, that's a huge outlier. I haven't touched a machine in the last 10 years where Ethernet and Wifi were not supported out-of-the-box. (Including my new Thinkpad, which I was weary about since it came with an Atheros Wifi module, but it too worked out-of-the-box without any tinkering).
These days, the biggest issues are with Nvidia GPUs from what I've heard.
Nouveau drivers are horrible for performance and the nvidia ones are not always great, if you can find a compatible one.
That being said - I can't compare with AMD as my last system of Linux with an AMD gpu for gaming was back when it was an ATI gpu. :p
From what you're saying, I guess those devices just aren't that common anymore?
Looking at the Asus spreadsheet for Linux my board supports Fedora and Ubuntu. OpenSuse and RedHat were listed as N/A.