The goal is reduced stack depth, not reframing the entire call model around not having a C stack.

We can't even reasonably rewrite getattr() without supporting callbacks from C into Python, so further generalisation is very unlikely.

But if you inspect the native stack of most Python programs, you'll see that it's mostly taken up with calls within Python code. Compressing all of those is a significant advantage, akin to inlining the Python code at compile time, even if it doesn't see "through" native calls.