Replying to Park skiers/riders out of the park

Why can't a lot of them actually ski/ride on other parts of the mountain? I was skiing the Outback at Keystone yesterday and I saw a few guys with tall tees and over-sized gear who were skiing very defensively (hunched over, hands way forward, backseat, etc.). I try to ski park every once in a while, but personally I love working on my form in bumps, off-piste, groomers, carving, etc. You would think that you would learn to ski moderately decent on groomers, and then ski park.