Now you're arguing something different. Just because all classes can, doesn't mean that they do, or that a general purpose tool (like, say, a garbage collector

Now you're arguing something different. Just because all classes can, doesn't mean that they do, or that a general purpose tool (like, say, a garbage collector) can assume that they do. It's not a question of efficiency, it's a question of what the language allows. If you're saying "everything has to have a vtable", then you aren't talking about C++.