I did not say, that every dynamic language has to implement it this way, but Python does. And Python was not intended to be a language for building up huge data

I did not say, that every dynamic language has to implement it this way, but Python does. And Python was not intended to be a language for building up huge data masses in memory, though it does not so bad in most cases (leaving out the mentioned ones). Pythons style has some advantages though. Simplicity and really a huge quantity of flexibility are two of them. (Traditional) Python normally is not a truly compiled language -- it is just a rather simple precompilation step that makes life easier for the interpreter. When you compile or "JIT" the code, you have more options. You see the whole program. The precompiler of Python does not! It just sees the local module. So, it can not find all classes that might enhance a base class. If you have any ideas, how to implement a better language, why don't you implement your own? It's up to you! (I guess, creating new (more or less useful) programming languages is the hobby of computer scientists anyhow)