[Zelizz]

People usually use it because piped input is a known interface, you don't have to go digging through a man page or help page to figure out what flag is needed to accept input from a file. "Data flows from left-to-right" is also very intuitive, and you don't need to know the specifics of how your shell interprets a command line to figure out where to put the input redirection in the case of a more complicated shell command.