However, hot water, is necessary to get rid of bacteria. Hot water and detergent together attack oils and grime. That oil and grime that you rinse away with the water contains bacteria. Without hot water, detergent is unable to be as effective. You may end up with an oily residue on your dishes or clothes.
Hot water also makes dishes able to air dry on their own very quickly. You can do your own experiment to watch this in action. Take two dinner plates. Rinse one in cool or even warm water. Rinse the other in very hot water. Set the plates down and watch them dry. You'll be able to see the hot water plate dry right before your eyes.
But why do we care about dishes drying quickly? Wet dishes and dishcloths are a haven for bacteria growth. Dishes that dry on their own, don't have to be towel dried, risking cross contamination. If your dishes are completely dry in your cabinets, you give no opportunity for them to be contaminated.
So technically, hot water by itself can kill bacteria, although it would have to be hotter than what we could tolerate. But the hot water we use is necessary to remove bacteria from our surfaces.