re: Giving back to the community

"They'd only have to feed back any alterations they made to the GPL'ed bits of the system."

correct, but the feed back only need be to those who have access to the binary.

could you image if every modification to un-released programs had to be accessible, sourceforge would have to be a slew of real-time feeds showing every key-stroke of every developer, flooding the system with crap code in progress.

the intent may have been to allow developers to only release tested code, basing that on distribution is genius.