I was using OP's verbiage, "open source."

But to have a patent, you must specify what it is you are patenting. Patents we're originally created to protect cooking recipes, so to do that, you would have to disclose the recipe and then no one else can use it until the patent expires.

This is why companies like Coca-Cola do not file for patents. Instead their recipe is a trade secret which they don't have to disclose to anyone.