I think Wikipedians are Wikipedians for a variety of reasons. Some of them are more
altruistic (free knowledge), others are more personal (but not necessarily negative),
others reasons are negative (pushing a point of view, advertising, vandalism, stroking
their own ego, etc).
But if we look at the group that are more-or-less altruistic, I sincerely doubt that we
can attribute their motivation to a particular author, open source software or whatever.
I've been well-aware of Richard Stallman, open source software, open research data,
etc, from before being a Wikipedian but those things didn't cause me to become a
Wikipedian. I think most Wikipedians are simply people who can see that knowledge empowers
people and enables them to live better lives, build a better society etc, and think that
Wikipedia is therefore beneficial to the world and something they feel able to contribute
to. I don't think most of them would think themselves as "commoners",
indeed I think most of them would be thinking you were talking about contributors to
Wikimedia Commons rather than the meaning you intend.
It simply makes good sense to contribute to Wikipedia.
Kerry