Just a speculation;

Apple must be working something really big for years with a lot of engineers shifted to that secret project. I am seeing lots of products not getting enough attention for the last 2-3 years.

- Safari is moving really slowly and not improved a lot except security-wise.

- iPhones haven't gotten a revolutionary feature for a long time.

- MacOS did not get significantly better comparing to last 3-4 years.

- Siri looks like a paused project.

and so on..