My user experience is that they threw something that worked for something that does not always (systemd does not work for me; failures to handle NFS mounts, etc, many little crap that does not matter that much expect: it worked before, correcting them was ununderstandably painy).
Basically, you found a bug in systemd, or possibly a bug in your distribution's use of systemd caused by a misfeature in systemd. That happens, especially with new versions that present major evolutions. Software can not be bug-free out of the box, it needs thousands, millions of users to explore all the corner cases. You had the correct reflex: you fixed the bug. Well done (no sarcasm intended)! But did you also report the bug upstream, so that the next person will find it less ununderstandably painful?
Unfortunately, that is not what some people do. Some people find a bug in systemd, or just hear rumors that there are bugs in systemd that may affect them, and so they decide to stick th SySV init. Fine. But they also demand support for their choice. They demand that new versions of distributions allow using SySV init, they demand that new versions of unrelated software, like KDE in this topic, work without systemd.
I will now be addressing these people: you, from now on, does not mean yeupou but these people.
First of all, you can not demand anything: you are users of Libre Software, probably gratis. You take it or leave it. You can make suggestions, express wishes, preferably politely, but in the end, you take what is offered and hopefully say “thank you”. Or you leave it, switch to proprietary commercial software, become a paying customer and find out that unless you are a major paying customer you still can not make demands, they will just be more unctuous about it.
There are a lot of bugs in systemd, there is no doubt about it. Most young software have a lot of bugs, and systemd is still very young. Or you can consider it as a new version of the software called “init system” that is a full rewrite: full rewrites also have a lot of bugs. But full rewrites are necessary in the lifetime of software, otherwise they are stuck with antiquated design flaws. As a full rewrite, systemd has a much better design than SySV init. This is not saying much: SySV init is made of a bunch of shell scripts; anything would be a better design. A better design means that in the long run, it will have much less bugs, much more features.
In the meantime, there are bugs. If one affects you, it is bad luck, because a new version is not released as stable unless it works for most people. Bad luck happens, we can only make the best of it.
If it is urgent, you can stick to the old version, the one that did work for you, of course. But that is only a temporary solution. Sticking to an old version of one software possibly implies the same for any software that depends on it. With a core component such as the system monitoring infrastructure, that will eventually mean everything, including the hardware. That is not sustainable.
As a user of gratis Libre Software, you are supposed to give back to the community. The first and foremost way to do that is to help fixing bugs. So if there a bug in systemd that forces you to temporarily stick to an older version, you are expected to file a good bug report. Otherwise, the bug may never get fixed. And if it takes too much time to your taste, then you install a virtual machine, you fire up your text editor and your compiler and you get to work fixing it yourself.
People who only whine and insult and never give back to the community only deserve to be mocked or ignored. People who help, as much as their means allow however small that is, deserve to be helped back.