Disclaimer: I am a former Ubuntu core dev (albeit nonpaid).
I feel Greg's keynote was a bit heavy-handed, but certainly a "better job" could be done to contribute more visibly. That said, Ubuntu, as a distribution, is doing a fairly decent job of getting novice users interested in tinkering with the plumbing. While, as a distribution, it is certainly not unique in that regard, I'd like to emphasise one thing:
We're missing the point, which is that it matters not which company is contributing "the most", because Ubuntu is also "about" enabling its users/consumers to become familiar with the plumbing so that they can contribute.
In the end, we're all consumers.
I've mentored several people (and continue to do so). We start with smaller things, like adding quirks to various HDA codec patches in ALSA, and progress to debugging interoperability concerns in the entire audio stack (e.g., why does GNOME's mixer applet throw an error? Oh, because it lacks an HDA codec patch. Let's fix that then figure out why this legacy audio app is abusing the ALSA API, etc.).
Enough already with assigning blame. It's time to demonstrate how "ordinary people" make a difference. In fact, I'm giving a talk at this year's Ohio Linux Fest on just how to empower users to fix their audio stacks.