Issue is that many large corporations use FLOSS internally with heavy extensions/modifications and never give back to the community. They don't have to, since all users are in-housr, and those tend to have access to the source code.

But that's ok. If upstream is somewhat active then it's just a pain to keep maintaining your in-house patches, compared to sending them upstream. So that's automatically a motivator. If upstream is not active, then it does not matter anyway.