Food, especially starches and proteins, clings tightly to plates and pans once it dries. Scrubbing them straight away with force is tiring and not always very effective. But water is a quiet worker.
When you let dishes soak in warm water with a bit of soap, the dried food softens, fats loosen, and burned bits start to lift. By the time you return, the sponge does more sliding and less scraping. In many cases, things almost wipe clean.
This doesn’t mean you leave dishes for days, but even a 20–30 minute soak while you do something else can transform a “hard work” sink into “quick rinse and done.”
You save effort, sponges last longer, and there’s less chance of scratching cookware by attacking it with too much force.