Dispatches from the compiler front

There a many variations of GCC that have not been contributed back. The code is available for others to pull in, sure, but (a) the community doesn't care about the forks and so has no desire to maintain them and (b) those forks are hairy and gross and otherwise not something you're likely to want in the first place.

It's much the same story as the Linux kernel. Being GPL only guarantees that some kind of non-binary and arguable human-readable code representation of a modification exists. It does not guarantee that those code representations are actually worth crap to anyone in the larger community.

The argument also fails to note MANY examples of BSD and MIT licensed software that has thriving involvement from the proprietary sectors.

Until the GPL states, "all modifications must be accepted by and committed into the original authors' tree before released as part of a product, unless he explicitly states he does not want the modifications due to lack of interest in the nature of the modifications made (and not solely due to correctable implementation flaws)" the GPL is really quite ineffective at enforcing any kind of community involvement or useful code contributions on the part of a company. It's really no harder to be a poor sport with the GPL than it is with the BSD license.