Is there no possible benefit for me that you might have learned something, or that perhaps you might now be able to tell me something I didn't know before?
You are moving the goalposts. I asserted there is no "massive positive externality", not that there is no possible external externality.
I do concede that maybe people who spend time in the library are more interesting conversationalists. I just don't consider this benefit to be "massive". Do you?