My tools serve me, not the other way around. It’s not worth the time and effort to wash by hand or sharpen on a whetstone. I don’t need an expensive knife to cook at home. A pull through sharpener and honing steel are adequate. Get the right material and you don’t have to worry about the metal in the dishwasher.
When all the utensils are in the rack, and you shove a knife in, it scratches against the other utensils, or even the plastic, and moves around depending on pressure during wash. That’s why it “can” dull your knives.
It won’t be as much of an issue with a serrated knife