As someone who boils her cast iron and puts everything else in the dishwasher: soap ruins cast iron and is antithetical to the point. HOWEVER. Boiling dishes and scrubbing them is perfectly valid. It's just harder to scrub a boiling dish without a handle than a boiling pan with a handle.
Imo, though 😅 I know nothing about anything I just take the best care of my cast iron as I know how