To compare Facebook (a frantic commercial venture that tramples on members and non members privacy and even admitting that they can make those members' comsumption profiles available for sale to third parties, among other niceties) with PBS (a free access public educational tool) does not seem fair, Regarding the supposed boost to PBS, let me remember that every time someone hits the name of a bulbous plant in the web the machine will invariably produce a PBS result. Therefore, a lot of people already knows PBS and uses it.