They view all of their products as appliances rather than general purpose computers.
They absolutely view phones as general purpose computers. It's why iOS is slowly turning into OS X.
Isn't it going the other way?
Not really. They are bringing features out on all of their platforms at the same time, now, so where is more feature constancy. Some iOS UI treatments have been brought to MacOS and some MacOS UI elements have been brought to iPadOS. But MacOS is not getting locked down the way that a phone is.