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.
The reason people used to not use soap on cast iron skillets is because soap used to have lye in it which would strip the seasoning from the skillet, most dish soap today does not contain lye and should be used to help properly clean the cast iron.
Also whenever I am helping someone with a new cast iron I always tell them not to worry too much about ruining the seasoning, because I have tried to strip a skillet of its seasoning completely by hand and it was so hard to get it all off