New tribes and adverse selection?

Booner [no longer around] said Sep 7, 2006, 4:14 PM:

 

People were born into hunter/gatherer tribes and remained in those tribes for life (or married into closely related tribes, or perhaps a tribe would split into two tribes).  The same is true for some modern tribes, such as the Hutterites.

However, we are mobile and can pick and choose, and come and go.  I see many Intentional Communities with some form of communal property or income sharing that are looking for new members, as opposed to expanding the group by having children.

So, if prospective members can pick and choose, is there an adverse selection problem?  Will the most capable and productive among us find the tribal model disadvantageous?