By the sound of your message, I'm guessing you examine every open source operating system, encryption method, web browser, word processor, music player, image manipulator, etc etc that you use on your computer. Most people don't. However, there are tons of professional security researchers, professors, college students, and hobbyists that can and do. If you're sending messages using an open source protocol, you can't hide it. Someone will notice.
With an open source protocol, it becomes simple to create (and open-source) fire wall software specifically for these systems that blocks messages based on type, source, destination, etc. Don't want messages getting out that reveal what you're using? Filter them. Don't want someone messing with your blinds from outside your network? Stop those messages. If you want to make it simple for people, give them a slider that lets them set, for the entire network, how open or closed their system is.