Point 4 applies as much in Linux as it does in FreeBSD. I've got binaries I compiled against 2.0 and 2.2 kernels in the mid to late 90s that will still run on

Point 4 applies as much in Linux as it does in FreeBSD. I've got binaries I compiled against 2.0 and 2.2 kernels in the mid to late 90s that will still run on 2.6 kernels today. Stable userspace ABIs are something that everyone agrees on.