Apple still issues software updates for many years beyond the competition. I have a 9.7" iPad Pro from 2016 (mostly a youtube and music device now) and I received a security update today. That is dedication to long time customers.

The products have matured. Comparing to last year's product makes no sense because most people don't buy new products every year

A lot of people buying the 17 are coming from the 12 or earlier, and it is a significant upgrade.