Used to be, if you wanted to build a robot “from scratch”, you needed to be an electronics engineer, or to be ready to spend quite a lot of time learning electronics theory and practice. In short, you needed to be ready to design and build electronic circuits from scratch and that’s no small feat. Of course, there’s still some knowledge of electronics needed, but the days of mounting your microcontroller chip into a blank prototyping PCB or breadboard are largely gone.
This is a companion discussion topic for the original entry at https://community.robotshop.com/index.php/blog/show/off-the-shelf-robotics-1