The novels of Jane Austen delight me, that's why they are literature. Ulysses doesn't delight me, but it does delight some people, so it is literature. If it delights some person it is literature.
You don't get to recognise Jane Austen as literature or not... I somehow get an image of the Dalai Lama laughing compassionately at such an expression of ego - Paul gets to decide what's literature

Then again I musn't speak for the Dalia Lama... just my image...
The plumbing manual "delights some in its practice", but it is not literature. The delight comes when you fix the tap, so its the practice that leads to delight. The Pali canon inspires meditation practice, and the delight comes from the meditation practice. The delight, in literature, has to come from the writing, not any practice it inspires.
I think we need a strict definition of "literature" or we just end up in declaring all writing to be literature. We need a word for delightful writing, don't we? Shouldn't that be "literature"?