The purpose of literature is to Delight. To create or endorse the Scholastic is a craven desire. It may yield a low-level self-satisfaction, but how can this compare with our joy at great, generous writing? With our joy of discovery of worth in the simple and straightforward? Is this Jingoism? The use of the term's a wish to side with the powerful, the Curator, the Editor: The schoolmaster's bad enough in the schoolroom; I prefer to keep him out of my bookshelf.
I think the question as to what is the purpose of literature is complex and not fully contained in the function "to Delight," but I get Mamet's drift. Readers don't want to be directed or schooled or preached to. They want to encounter, explore, discover for themselves. The delight is in exploration and discovery.
A number of novels pop to mind when I consider the delight of well-crafted literature (of course, my idea of "delight" may seem a bit twisted, as evidenced by my list--the line between delight and disturb may be thin for me). Here's my short list:
Geek Love (Katherine Dunn)
Life of Pi (Yann Martel)
Ellen Foster (Kaye Gibbons)
Speak (Laurie Halse Anderson)
Getting Right With God (Lionel Newton)
The Left Hand of Darkness (Ursala K. Le Quin)
Their Eyes Were Watching God (Zora Neale Hurston)
Like Water for Chocolate (Laura Esquirel)
Microserfs (Douglas Copeland)
Something akin to "delight" overcame me when I read these novels: I was transported to a unknown place, met a new sort of person, bumped up against a fresh idea; I encountered something for the first time. And I was delighted. I suppose I "learned" something, but it wasn't the author "teaching"; it was the experience serving as instructor.