Okay why do we need literacy if we have such beautiful screen readers? Maybe because it's better when you actually absorb these fundamental skills rather than rely on a disability aid to relieve you of a self imposed handicap.
It's little effort for a large benefit. But anything you learn past middle school in formal education is a moderate to large effort for a small to neglectable benefit. And you'll forget it anyway if it is uninteresting and not useful in your daily life.
Anything interesting or useful in your daily life, you'll pick up by yourself even without formal education.
Knowledge is not a tool for answering the absolutely minimum questions you encounter in daily life, but a way of seeing the world. Reading allows you to use language in ways you could not imagine with spoken word alone, just as math or physics or computer science enable new ways of thinking inaccessible without intense study.
Our brains can't hold infinite amounts of data and a lot of information will become inaccessible if not used regularly. This is also why most of us do not speak twelve different languages, despite this being a supremely useful skill that is relatively easy to pick up compared to semiconductor physics.