Sometimes the manufacturer makes it difficult. Replaced the light bulb in my parents' oven last week. The manufacturer only sold the bulb with the entire (expen

Sometimes the manufacturer makes it difficult. Replaced the light bulb in my parents' oven last week. The manufacturer only sold the bulb with the entire (expensive) housing as well. A bulb! We managed to find a supplier with a compatible bulb (which meant a quick swap). I'd like to think there was a reason the manufacturer wanted the entire housing replaced?