Yes as a matter of fact, a drop, or two, just a drop or two, of dish washing liquid soap, messes up the surface tension of plain water, so it is absorbed by the fouling faster. It actually does reduce and simplify your cleaning.A little soap don’t hurt, I lean with hot but not boiling
I think you are myth-ing the point. It does not happen to all barrels.I've used boiling water with a cap full of Murphys oil soap. Have used this method for as long as I've been shooting muzzle loaders and am not changing. Flash rust is a myth using boiling water. I've never seen it happen.