[pritovido]

He never says that. You probably could do the same with multiple 8 bit arduinos as well, I have done something similar myself with klipper. But your life while doing that will be miserable.

The first thing you have to add for anything serious is a real time clock that Raspi DOES NOT HAVE by default.

What he is saying is that Linux is not intended for that,not designed for that, because it it not a RTOS, and it is huge.

You can fill the void, but you will be reinventing the wheel. Low level hardware design is painful.

Linux is extremely complex, too complex for a person to understand. It will take man-years of work to handle all the details, that is, it cost hundreds of thousands of dollars just in salaries alone.

It is way easier to do what this man has done. And then if you want you add an additional raspi with linux as the controlling UI.