I've definitely had this happen. With my own code, even. I build something complex, it's released to production, and a few months later I realise that something about it should be done in a different way, so I look at it, and other people have already built on top of the thing I wanted to change.

On the other hand, if you can't figure out what something is for, sometimes the easiest way to find out is to remove it and see what breaks. Maybe that's not such a great idea for that load-bearing stud, but in software it's easy to undo.