I'm not sure how I can explain it much better, I even wrote example code after all, but I'll try...

> So if you are embedding python by dlopen'ing libpython.so

Neither me nor Laszlo are using/embedding or otherwise involving Python (directly/intentionally at least).
We just want to load some .so file.
That .so itself might then use libpython. Or use a library that uses libpython. Or uses a library that uses a library .... that uses libpython.
And how could we know whether SOME library down that dependency chain uses libpython or not?
The result is that now EVERY SINGLE LIBRARY IN THE WHOLE SYSTEM needs to be loaded with RTLD_GLOBAL.
Because a library 50 dependencies down that uses python might break otherwise and there's not really any way to know.

Just to try be very clear: We are not users of libpython, we do not write or use any python code ourselves (except through indirect dependencies) and we are still hit by this issue.