I agree emphatically. For max performance (for both climb and top speed) you need the engine to be delivering the most power possible to the prop. This is typically the maximum allowed rpm for an aircraft engine. The constant speed prop governor will then vary the pitch between low and high as necessary to maintain that rpm, maximizing the thrust for any given situation. The only car analogy that fits in this case is a car with a continuously variable transmission, but people almost universally reference simple manual transmissions in their descriptions.