Many, perhaps most, very learned people prefer the company of their books to sitting in a crowd listening to history and art being mangled; furthermore, it is unlikely that the venerable scholars will stand up afterward to declare, This lecture was a load of crap. The more profound a professor's distaste with the proceedings, the more likely he is to melt away at the end of the talk.
On academic conferences, p. 179 - Sex, Art and American Culture : New Essays (1992) - Junk Bonds and Corporate Raiders : Academe in the Hour of the Wolf