[unstruktured]

pypy and cpython don't mix well with each other so you have to create a whole new universe of packages for pypy. Interop with c libraries also adds complexity to the transition.

In addition, vanilla python is finally starting to tackle the worst performance problems (like the GIL getting removed for instance), so they might catch up to pypy eventually. There's also several different JITs installable into cpython systems these days too which is less painful than switching to pypy.

Personally, I am saddened pypy didn't replace standard python, but even in my own career I couldn't find a big speed difference in practice because all the heavy lifting utilizes C, C++, or fortran libraries wrapped by thin python apis.