In artworks I've seen depicting battles, horses are never shown with any barding other than a chamfron, and even this is rare. More often than not, horses are depicted wearing only a caparison or nothing at all. Were they expected to be only used as transportation? To never be used in battle other than chasing defeated foes?

Either way this clashes with the fact that horses were both very expensive and a sign of status, so how accurate are these artworks? Wouldn't every horse expected to see combat be at least covered with a caparison?