Our recommended usage of pybind11 has evolved somewhat in the past year (e.g. getting all the wrapped pybind11 into a single .so library file), but our dev guide pages haven't fully evolved to match our current usage. For example, Jim Bosch pointed out the first note in this section of the How To, which is the opposite of current policy. There are likely other places. Someone with significant recent experience with pybind11 should update these two guides to properly reflect how we're using it now.