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.
From what you're saying, I guess those devices just aren't that common anymore?
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
Looking at the Asus spreadsheet for Linux my board supports Fedora and Ubuntu. OpenSuse and RedHat were listed as N/A.