Except it's not. If I hit a bug in the NFS code, who at Debian will help me? Nobody. The bug report is opened and the buck is passed upstream. Now they have to hope the upstream maintainers of the NFS code care to fix it. They might not be interested especially if the distro is shipping an older release they no longer wish to maintain.

If I hit a bug in the NFS code on FreeBSD, I open a bugzilla issue first, but get the attention of Rick Macklem. If I hit a bug in the posix shell, I contact Jamie Gritton. If I hit a bug in the VM subsystem, I want to talk to Konstantin Belousov. A weird timekeeping issue? Most likely our resident Time Lord, Poul-Henning Kamp. A C conformance issue? Presumably David Chisnall. Even our compilers have patches required for our codebases, so we have compiler maintainers. If I hit a bug I have a team of people to reach out to.

All of these people have a vested interest in bugfixes and maintaining the code within our supported releases. You do not have this luxury in the Linux world. At best you can hope you have a support contract with RedHat or someone who can pay a competent employee to figure out how to fix it if upstream refuses to get involved.