I think moot was pondering why you were claiming there are many volunteer contributions to 4chan's code, when 4chan's code and tools have been closed source (i.e.: presumably in-house developed only) since the start.
This doesn't really answer the question how you know that "4chan has had a lot of beautiful code submitted by volunteers every year." when it's not open source?
Oh. I've been friends with several 4chan janitors/moderators over the years. But there's also occasionally leaked images of the software behind the scenes.