Being different
The opposite issue is differentiation. Apple is a product company, and for all of the blather about artificial intelligence, the one thing that matters is how the tech can develop into a part of its product family. In the event you glance at the numerous existing machine intelligence features already in its products, you’ll see that almost all of those complement existing hardware. On the subject of Apple Intelligence, for Apple the North Star should be the necessity to ensure it continues to supply something unique.
To some extent, doing this with AI is fundamentally difficult, as this type of general purpose intelligence will eventually develop into a homogenous block of various models using similar data (all the info on this planet) to tell responses to similar questions.
With that inevitable homogenization, AI services may yet develop into utilities moderately than differentiated products. So, it could make sense for Apple to avoid developing its own general purpose AI, resolving to create specific solutions that work way more effectively for specific use cases and counting on partnerships with these emerging AI-as-a-Service corporations (AI-ASS?). That appears to be the Apple Intelligence way.