I know that “Everything is a file” means that even devices have their filename and path in Unix and Unix-like systems, and that this allows for common tools to be used on a variety of resources regardless of their nature. But I can’t contrast that to Windows, the only other OS I have worked with. I have read some articles about the concept, but I think they are somewhat uneasy to grasp for non-developers. A layman’s explanation is what people need!
UNIX philosophy says: do one thing and do it well. Make programs that handle text, because that is a universal interface.