I think most people don't upgrade their phone until something breaks, maybe that's what is driving cycle length. That underlines the marketing genius of non-user replaceable batteries, which are usually the first thing to go.
Agreed, though I also add "unbearably slow" as a form of being broken. Whether you view this as the cost of running newer software/webpages with fancier animations, a collective form of donations to developers using less efficient languages/frameworks, or an externality pushed onto users by the ad industry may vary.