grep is simple to use from a simple command. Setting up a Java server and maintaining it is quite a different challenge then running a command with a few parameters. I wouldn't use it because if it goes down, fuck. If I need to extend it or decide to change something in there, fuck. I would want to use something that is easier for me to fix and maintain or my coworkers to fix/maintain, then have a product built from multiple languages that require too many different types of people to keep it running.