Yeah, the serious answer is what I'm worried about. See my other, more detailed reply, but with things like SELinux and PaX on Linux weakening the "OpenBSD is where security happens" story, I don't know how to avoid a monoculture that is compellingly better on one axis (community, hardware support, etc.) from eventually outpacing its competitors on every other axis.
Or phrased as an engineering problem: if we believe monocultures are bad, without breaking the constraint that meritocracy is good, how do we structure our projects and communities so that people work on e.g. the BSDs instead of making Linux better than the BSDs on all axes?