Elders have at least three masteries. They earn that title for having the masteries, not earning the masteries because they have the title.
Unless you're talking about simply old villagers. In which case, of course, they work, though women over 50 can't bear children. They also move much more slowly; they're more useful for tasks like research or healing, where they don't have to walk all that much; men are also useful in parenting still. Being kind of a non-critical skill, I don't mind if they do it slowly.
Elderly villagers are not good for farming or building typically; the distance they have to walk at that slow speed is just so far, that their walking speed slows down their work and their gaining skill much, much more.