Because CS101 should teach you about basic programming techniques, like how to open a file for reading or writing. In order to understand how to open a file, y

Because CS101 should teach you about basic programming techniques, like how to open a file for reading or writing. In order to understand how to open a file, you need to have a basic understanding of how permissions work. In order to understand how permissions work, you need to understand how mode bits work. This is really basic stuff, but I'm not surprised that most developers think it is beneath them. "That's sysadmin stuff; I don't need to learn that." These are usually the same developers that think chmod 777 is a fix.