An OS kernel is a bounded problem, it abstracts hardware, enforces some security constraints, and allows user programs to run. So it's not really that hard to h

An OS kernel is a bounded problem, it abstracts hardware, enforces some security constraints, and allows user programs to run. So it's not really that hard to have a consensus of what Linux should do. Linux also has the (unique to it) idea that the kernel and the rest of the OS are not the same thing. There is no other integration point than the ABI for userspace. And OTOH, Linux userspace is ridiculously de-centralized. There's competing distros, init systems, C runtimes, memory allocators, filesystems, etc. And that's not even taking into account the absolute chaos of the Linux desktop.