Not that there's anything wrong with that and it certainly seems like Apple has been investing in-house pretty heavily in recent years for Siri improvement.
That said, in my limited experience, organizations doing NLP also have something to offer by way of TTS too.
One of the ideas is that most ML researchers want to publish their work and Apple wasn't allowing it. Allowing ML researchers working at Apple to publish in this journal was they only way they were get more ML researchers to work for them.
I'm guessing Apple simply had to make this change in order to stay in the game.
Did you ever see the list of authors on publications of CERN? Or take this example: [1].
[1] https://www.nature.com/news/physics-paper-sets-record-with-m...