All models are wrong, but some are useful. Thinking of evolved features as having a purpose is wrong, but it is also incredibly useful.

Why do we have eyes? In some sense, there is no reason, just a sequence of random coincidences, combined with a slightly non-randon bias refered to as "survival of the fittest" (itself an incorrect model).

However, saying that we have eyes to see has incredible explanatory power, which makes it a useful model. Just like Newton's law of Universal gravity. We've known it that is wrong for a century at this point, but most of the time still talk as if it's true, because it is useful.