It's been mentioned time and time again, but it's worth mentioning again — Windows maintaining backwards compatibility is what maintained its hegemony, as compared to it, Linux and macOS look like hobby projects. For the young as well, because games still run on it, without worrying that Apple will invalidate their library due to not being in the mood to maintain 32-bits APIs.
I bet if you pay Apple similar amounts of money per year, they'll keep specific APIs available just for you.
And it's not like updating the app to a new iOS version is a massive undertaking, in most cases it's just a matter of opening the project in XCode, adjusting the OS version, compiling and publishing it again.
[0] https://money.cnn.com/2015/06/26/technology/microsoft-window...
And also, it's unreasonable to expect all software projects to need updates, forever. My hammer doesn't need updates.
Something that just has to be done, and not doing it has a clear cost.
Linux has dedicated people working for free to support the weirdest hardware and software