If you are part of a younger generation, or someone in or just out of school, you may have a distorted sense of the skill of most smartphone users. Those of us in 9-5 jobs, where the average iPhone user is 40-50 years old, see how clueless most users are about their phones. The average iPhone user doesn't even know how to organize their home screen.
Those of us who are more keen to public observation can clearly see the average person can still get to know features of their phone.
The folks using flip phones and the like are the customers that Apple must appeal to to increase its iPhone sales. Virtually all of the "advanced users" already have smart phones, and in the USA, the vast majority of those users have iPhones. There aren't that many existing smartphone users to convert in the USA, where Apple dominates the market.
I don't know why you think you know what Apple "must" do. You have no idea.