[pabs3]

It is fairly trivial to test other init systems using virtual machines, booting off another installation on USB or even by installing the other init system and rebooting. Also, delegating the testing to those using sysvinit and NM would have been just fine too.

[rleigh]

When I was maintaining sysvinit and initscripts, and testing changes to these, as well as initramfs, lvm, and all other associated packages critical to booting, that's exactly what I did.

Before upload of every single release, it would have been tested on a battery of virtual machines using various different configurations, plus bare metal including non-x86 architectures (powerpc at the time). That was sufficient to catch the vast majority of regressions upon common and not-so-common setups. When a single mistake could effectively brick thousands of installations, you do have a responsibility and duty of care to not ever break system boot.