Is it possible to avoid the public goods problem altogether?
As Lynne Kelly indicates, knowledge is a broad public good, so it is kept by higher priests and only transferred in private ceremonies to the initiated in indigenous cultures. In many senses, we've brought the value of specific information down dramatically, but there's also so much of it now, even with writing and better dissemination, it's become more valuable again.
I should revisit the economics of these ideas and create a model/graph of this idea over history with knowledge, value, and time on various axes.