> Linus' rule also has disadvantages as it blocks real innovation in the Linux ecosystem.

Block real innovation like what?

> Granted, Desktop Linux doesn't need another Python 2 -> 3 or X.org -> Wayland deathmarch...

That's all userspace? Userspace doesn't care it breaks. That's why userspace sucks. You need to keep compatibility if you want to have a stable base to build something. That's why we have (sometimes silly) standards like SUS or POSIX.

"we do not break userspace" at least garantees that you need to fix only the userspace, and not the whole thing all the time.

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.