Shaw and Wilder

Thornton Wilder visited Bernard Shaw -- and it was dislike at first sight. (According to Literary Anecdotes.)

Why?

My first guess: Both men were accustomed to being fawned over by their visitors. Here, neither condescended to do any fawning. And if Shaw hadn't read any Wilder, I can imagine that any conversation was one-sided. (I remember reading that John Dewey and Sinclair Lewis attended the same party, and each was miffed at the attention the other received.)

Or maybe Shaw was jovial, witty, and cynical...and Wilder was not that sort.