A Version of the Intentional Fallacy
Although the author and the poem are born in the same instant (the author is not an author until he is the author of something), the former is always for the sake of the latter. We have authors so we can have poems (or plays, or novels, or whatever); we do not have poems so we can have authors.
It is therefore fallacious to judge a poem by how well it expresses the author’s intentions; we should instead judge an author by the success or failure of his poems.
In order for the poem to be a successful poem, it must be successful at something other than expressing the author’s intention.
The successful expression of the author’s intention may assist the poem in achieving this something else, or it may hinder it, or it may have no effect at all.
Perhaps it is objected: But surely someone must intend that the poem achieve this something else.
I say: Maybe, maybe not. We desire this something else; it is why we have poems, and we have authors in order to have poems. How it is that it comes about — whether because the author intends it or for some other reason — is immaterial.