Why is UX so hard?

I've often wondered, why is UX, or user experience, such a challenging aspect of product development? It seems like something that should be relatively straightforward, yet it consistently proves to be a roadblock for many teams. Could it be that we're simply not prioritizing it enough? Or is it a deeper issue, like a lack of understanding or the right tools and methodologies? It's a question that deserves further exploration, as the quality of UX can have a significant impact on the success of a product.