So you are worried about soap affecting the seaosning on your cast iron, but are fine with stainless steel utensils stripping it all off?
No I'm not worried. Stripping or weakening patina is a thing that should be avoided but occasionally happens. Taking care of the patina is a matter of convenience, comparable to cleaning your plates before they're crusty: Both situations can be fixed, by re-seasoning and heavy scrubbing respectively.
You wouldn’t wash your plates and dishes with just hot water and some light scrubbing, so don’t wash your pans that way.
First off yes I do if there's no grease to get off, secondly plates and dishes don't get heat-sterilised on every use.
Modern dish soap wont do anything to harm your pans and even extend the longevity since they take off leftover food particles that house all sorts of microbes.
Dish soap is good against fat, it allows it to enter emulsion with water. It does nothing to starches which are already perfectly soluble in water, and preciously little to proteins which tend to have quite good solubility in water.
Not using soap has two principal reasons: a) it's unnecessary, boiling water already takes everything off but the grease and b) I'm going to add some oil afterwards anyway why take off all the grease? If I'm just a bit lucky I don't need that extra drop of oil at all what stays on the pan is sufficient.
all sorts of microbes.
Oh no! Do you have allergies? Other kinds of autoimmune disorders? I don't. You can bet your ass that I scrub everything that has touched raw meat thoroughly (short of the pan that gets sterilised by frying), but don't expect me to use soap on a plate with breadcrumbs and a spot of jam on it.