Bad analogy. Some gearheads have removed their A/C to reduce weight and increase performance.
If performance is your main priority, then the adding of features that may hurt performance is a legitimate concern.
Ok, look at it this way. Some people are willing to give up bleeding edge performance for the convience and fun of having all your needs taken care of on one monitor. The people that want perfect PC only monitors (like car gearheads) can buy an Eizo.
Of course this is all assuming that monitors with multiple inputs have poorer performance, such as more imput lag. No one has proven this yet.