It looks like python@ is more appropriate for basic questions about the usage of the existing language. My question is about internal mechanism that supports language design. Not only asking about existing behavior, but also about why this behavior can not be changed. I thought that people who are writing Python in Python are more skilled to answer such questions. In the end, I understood that PyPy project was created so that people who can't read C could still understand and experiment with their own language, no?
We can explain to you how stuff works. Why not change it? Because python-dev said "no". Please take it with them, we don't deal with language design. People *can* experiment with the language whatever they like. If they find their experiments working, they can take python changes with python-dev, we'll not participate in this discussion. You're not asking how it's implemented though, you're asking why it works the way it works, and this is totally not for us to answer - we just copied cpython semantics and this is what we're going to keep. Please take this discussion somewhere else.