Yes, that's unfortunate, but Apple isn't intentionally trying to prevent them from using the other software. It's just a bad consequence of the way the API work

Yes, that's unfortunate, but Apple isn't intentionally trying to prevent them from using the other software. It's just a bad consequence of the way the API works. Note that they would be free to use these services if they used an alternate mechanism of talking to them (e.g. built direct support into the app).