the days of 1 year, 2 year upgade "cycles" ended when the carriers stopped subsidizing phones a few years ago. There's nothing magical about 2 years or three years and nowadays not much changes year to year except the hype & camera. Most people aren't buying new computers every 2 years... so why buy an iPhone? It costs as much as one. It seems like unnecessary churn & waste for marginal benefit. Most of these iPhones can work perfectly fine beyond 3-4 years if they're taken care of (and kept on their original OS)
Except you can still do 1 and 2 year upgrades by trading your phone in on programs like ATT NEXT and Apple IUP.