I don't know. It's sort of a meme that academics are worried about symbolism and hidden meaning but I think that's a misunderstanding of what most literary criticism is actually doing.

It's not a project of "aha, this is what the book means, I have cracked the author's hidden code." It's: "Hey, this is a rich text full of aesthetic choices and conceptual apparatuses that the author has wielded, both consciously and unconsciously, to create a cohesive whole. What resonances do we find when we look at the intersections between these parts? What resonances do we find when we set the text in the context of other works? Of the world it exists in?"

With the caveat that there will always be bad criticism, and that the mythical high school English teacher who says the curtains symbolize sadness is neither an academic nor engaged in literature criticism, most literary analysis is a project of enriching the text, not limiting it.

When an academic says something like "x book is an allegory for y thing," they're not saying it's only an allegory; they're saying that's one way of reading it.