Because it is the OS that broke backwards compatibility and caused the application to stop working. That the kernel is used in "servers, computers, smartphones

Because it is the OS that broke backwards compatibility and caused the application to stop working. That the kernel is used in "servers, computers, smartphones" and wherever else metric of popularity doesn't magically make applications run. Developers who work on libraries that are relied on by others to provide basic functionality (like GUIs) not breaking their APIs is what make applications run.