Hopefully this isn't too broad of a question for here, but I am an amateur programmer who doesn't have much experience with super complex programming as of yet (I've mostly used C for basic microcontroller and interface stuff so far).
I've noticed that a lot of applications have odd filetypes to store text data that seem to be different for the sake of it. For example, Valve video games store user settings in 'config' files that can be easily edited by any text editor. Is there a specific reason for this?
In other words, assuming the data doesn't need to be encrypted or secure in some way, why not store plain old text data in a plain old text file? What are common purposes of storing plain data in odd file types?