There are lots of embedded systems beefy enough that Fedora is an appropriate choice.

Not really. Fedora IoT only supports x86_64, aarch64, and armhfp, which has some intersection with this space, but not a lot.

Regardless, that wasn't really the point of the article.

There is lots of embedded that uses x86 or arm. Lots of embedded isn't significantly power or size constrained and volumes are very low so software development costs dominate over hardware costs.

But agreed, those aren't the point of the article.

"Embedded" is a big space.

Something that is not power nor size constrained doesn't really fit most people's definition of "Embedded."

Example: the computer in a CNC machine.

Just because you can doesn't mean you should

Article title doesn't contain "from scratch", so I will rewrite your example as "So, you want to build AM radio?" and my response will be "No, I want to build FM radio, because of tons of FM radio stations available to listen".

The article isn't even close to being about building a linux distribution. It's about embedded electronics engineers moving from microcontrollers with custom embedded firmware to SBCs using minimal linux for embedded systems. So accepting your revision, the response would be "no, I want to buy a stereo system".