I would say your comment either shows a lack of understanding, or that you completely missed the point.
> The example of "writing your own script" is no different to a non-systemd system. Why would a script work or not work based on systemd?
Of course, you can write the service itself in Python or Ruby or whatever regardless the service manager. The point is that with systemd, or upstart, or other service managers like this that make things more declarative (launchd?), you don't have to write a script to manage the service at all.
On systemd, you declare which services yours depend on, how to run it, which user should be used to run your service, and many things are handled for you, including many security mechanisms you don't need to think about and provide further config for this stuff that would be a mess to handle with the traditional way of writing a custom rc script per service.
The problem is not being able to write in languages like ruby or python. It's to have to write something at all.
systemd makes many things declarative that were historically procedural, potentially painful to debug, code.
This eases distro maintenance and I suppose is one of the top reasons most distros adopted it.
wrt the Unix philosophy, discussions about it related to systemd are often (always?) too abstract to be useful, I'd suggest talking about specific problematic points.
No.
- You claim that the Unix philosophy only survives to the GNUtils. Well, that shows to me a lack of understanding what the philosophy is about. Everything is a file is similar to the OOP approach of everything is an object. I recommend watching Ken Thompson when he was young here: https://www.youtube.com/watch?v=tc4ROCJYbm0
It does not capture all the UNIX philosophy but it does extend on the reasons why that philosophy works well. The philosophy is bigger than that of course but it helps serve as a counter-argument.
- The example of "writing your own script" is no different to a non-systemd system. Why would a script work or not work based on systemd? You mention as example FreeBSD debugging a shell script. Well, others use proper languages such as ruby or python. Everything that can be done via systemd I can do without it too and, in fact, have been doing so. Ruby essentially runs my system as the primary layer on everything (granted, it runs Linux, and thus mostly C, and ruby is at the end of the day a syntactic wrapper over C). I never understood why systemd would matter. I read the advertisement of the systemd devs - none of this applied to my use cases, so I never "embraced" systemd, simply because I never needed it. I did point out the increased complexity of it as a negative trade-off and this has been true til this day.
- Former "hater" also implies that criticism is not based on rationale and logic. This is not the case either. It's funny to me how the pro-systemd camp isn't really able to come up with compelling arguments on their own.