(Bringing my response from core-mentorship over to the main tracker)

These APIs are exposed to embedding applications via the pylifecycle header: https://github.com/python/cpython/blob/master/Include/pylifecycle.h#L143

While we technically *could* deprecate & remove them (since we're not currently using them for anything), the current cost/benefit assessment is that it isn't worth the API churn (even for the underscore prefixed _PyFrame_Init API) when it's relatively cheap to keep them around as no-ops.

Given that they exist in the code base in order to continue exporting the symbols though, future maintainers are entitled to expect that we'll keep calling them in the appropriate places, such that if anyone *does* add code to them in the future, that code will "just work".