Huh, I dont know where you are, but here in the States I got my iPhone through 0% financing (amortized over 2 years) program that allows you to get a new phone every year and comes bundled with AppleCare+
The iPhone upgrade Programme which I presume is what you are referring to are not popular outside US, and Apple barely advertise about it. ( Which is why I said push in the original sentence ) And it is only available in selected countries and under some condition.
I evaluated it here in UK and it just didn't make sense for me. It was very expensive -- slightly less than buying a phone every year, but much more than doing it every two-three years.
The iPhone Upgrade Program is exactly the same price over the full course of the loan as just buying the phone with AppleCare. If you don't want the AppleCare, "iPhone Payments" is exactly the same price overall as just buying the iPhone. Both are 0% financing.