Breakages of userspace are almost always unintended consequences. I don't have examples to the contrary, but I believe that intentional breakages and redesigns

Breakages of userspace are almost always unintended consequences. I don't have examples to the contrary, but I believe that intentional breakages and redesigns are almost unthinkable because of Linus's rule. Significant changes in the kernel already often need years to land because of the multitude of configurations and interfaces that have to be supported. And even longer to deprecate and remove. Not necessarily a bad thing, just the price of success. Large-scale breakages like the Wayland transition affect the whole Desktop Linux ecosystem, and are just an example of what mayhem fundamental changes can cause.