Unified low-level "linux plumbing" architecture is something that a lot of people have realized is needed for a very very long time.

This is a major criticism against Linux distributions from the beginning. Especially from the *BSD camps.

And Systemd project is full of people actually putting the work into solving this major problem.

You are right that it isn't innocent. It is actually very sophisticated and probably very wise thing to do. It is helping a lot of people out.

What's a "major problem" to you is the best and unique aspect of having different linux distributions to others.

The actual major problem is that systemd developers wasn't being contempt with just building an opinionated system and let it rise on its merits, instead they choose to use its status to "gently push" their opinions on everyone else.

If your distribution is already content to ignore any efforts at standardization in favor of "unique aspects" then I don't see what the problem is. You can go about your business and ignore systemd, or choose to adopt it on its merits. It's entirely up to you, nobody is using any status to push opinions on anyone.

Also you're ignoring the last part of that sentence: "where there's really no point at all in doing so". That's the most important part. If a distro has a real reason to deviate then that's fine. If a distro is deviating for no reason then that's doing a disservice to its users, and you can expect anyone who ships other things for that distro to be upset with them for pointlessly making extra work for everyone else. It's not just the systemd developers who will be inconvenienced.

A distribution isn't a single individual. It consists of different people, developers, maintainers, contributors etc., who are at different levels of acceptance or appreciation of various features of systemd. It isn't as simple as being content with it, or adopting it. In a diverse distribution like Debian there are constant debates about various features of systemd, and that's not only because they haven't decided on systemd yet, but because systemd project isn't also making their job easier by constantly adding new things and gently pushing distributions to use them.