It wouldn't be difficult to disallow these cases, but is that a problem after all? My opinion is that the requirements should be shaped (also) by what logic is

It wouldn't be difficult to disallow these cases, but is that a problem after all? My opinion is that the requirements should be shaped (also) by what logic is required on the implementation side. And in any case, there's no justification to change the style and make an incomprehensible thicket of vague "abstractions". There's at most one to write slightly more logic.