The "target SDK" and "minimum SDK" versions can be set separately. It's mostly just a cultural norm in the Apple ecosystem not to support older versions.
This is supported by 1. Apple being relatively good at releasing new versions iOS for older hardware. 2. Users (at least historically) typically being on a ~2 year upgrade cycle. But it's also just the case that the Apple ecosystem (including on macOS) tends not to value backwards compatibility as much as other ecosystems.
This is supported by 1. Apple being relatively good at releasing new versions iOS for older hardware. 2. Users (at least historically) typically being on a ~2 year upgrade cycle. But it's also just the case that the Apple ecosystem (including on macOS) tends not to value backwards compatibility as much as other ecosystems.