systemd is not an init system; it _contains_ an init system. It is a huge swatch of the whole userspace of a Linux system up to shell or GUI sessions - and having an init system was just an excuse; and in fact, the systemd point brought up in the linked article is unrelated to init systems.

There are quite a few init systems: The venerable sysvinit, runit, s6, openrc and others. You don't like upstart? Ok, choose another one, there are many. Here is a comparison table by the Gentoo folks:

https://wiki.gentoo.org/wiki/Comparison_of_init_systems

As for the claim of "almost all sysvinit scripts contained several bugs" - that's both hyperbole and false. Plus, you seem to be implying that systemd has not been troubled by bugs, which of course it has (and that does not disqualify it; the fundamental design and organizational nature as a project are the disqualifiers).