If the concept is that protocol requirements represent the "customisation points" of a protocol, shouldn't this apply equally to conforming classes and subclasses with inherited conformance? So I would be in favour of fixing this. Conversely, perhaps protocol extension methods etc not declared as protocol requirements could e.g. elicit a compiler warning when "overridden" by conforming classes/subclasses with inherited conformance (since they are not intended as customisation points)? I think these changes would aid reasoning about protocols and reduce bugs.