"the JBoss development community, for example, is nearly 100% Red Hat employees"
This is no surprise, while JBoss is Free Software it's still not available in distros like Fedora. If Red Hat own employees can not manage to massage JBoss so it can be accepted Fedora-side, who else is going to look at its code?
There is a major gap between something released cleanly enough so another employee can look at it with some hand-holding using internal resources, and something that can be built and deployed by a third party alone (and by built I mean built as good as the upstream binaries, not a frankenstein assembled with sticky tapes). No one is going to contribute to something he can't build reliably.
When you're doing internal development you can use all sorts of shortcuts such as freezing a component version and pretending it is not evolving anymore upstream. But external developers are only going to accept common standards (same components as every one else, latest version accepted by everyone else, standard build system, etc)