You are right, but that is throwing the baby out with the bathwater. There is a limit to what can reasonably be expressed in a type system but that doesn't mean

You are right, but that is throwing the baby out with the bathwater. There is a limit to what can reasonably be expressed in a type system but that doesn't meant we should just give up. Moving a group of methods that just throw a NotImplementedError to a different interface so that you can talk about then seems fairly low effort and high value.