It uses all the cool features of the kernel. It's configured with text files, and has an override system that works great with the Linux filesystem layout and package manager -- much better than SysV init, by the way. And it handles a lot of little annoyances that have long been a thorn in an admin's/user's side on Linux.
I'd argue the better parts of systemd (it's not all bad but there's a lot of low-hanging fruit for all of us to gripe and bicker about) are the imaginings that came from launchd. That for sure was more UNIX centric than "linux" in particular.
You're right that the criticism "just become windows" seems weird - if anything else one should just say "get a mac" since that's where a lot of the launchd ideas originated.
For instance it's very reliant on cgroups, a Linux-only feature. The main project rejects even trying to be portable. This ensures there's no such thing as accounting for that some feature might not work on FreeBSD, because the project just clearly states that it won't be a thing on *BSD.
I don't understand this idolisation of 70s mainframes that "hardcore" Linux users all seem to fight for. Systemd features can all be turned off if you want them to, but every day more and more alternatives go into maintenance mode because nobody uses them anymore. Inetdwas great when it was invented but we've moved past that point more than ten years ago.
When I'm tinkering, I love the great hacks I can apply by modifying system shell scripts, but I mostly just want my computers to work for me. The old ways of randomly placed dot files, custom service scripts (and formats) and modifying scripts that I shouldn't need to ever touch anyway because they conflict with another cobbled together script have caused me more headaches than systemd ever has. I wish system's docs were easier to find, but even the obscure man page names are better than comments in bash scripts somewhere in /etc/init.d.
I've been an user of Linux since quite early on. Back then I recall a lot of enthusiasm for the desktop and attempts to make the user's life easier. Things like YAST were a selling point, there was the framebuffer console for a prettier boot, and Enlightenment if you wanted all the gratuitous eye candy your CPU could handle. There seemed a lot of interest in making things better and look cooler. It was a world full of possibilities, back when the Windows users rarely got more than changing the UI font to something weird.
Today there's this weird attachment not only to the days before that, but to the things that sucked. Like there's some people that are nostalgic for FTP for some reason I can't quite understand. FTP is an awful protocol, and which resulted in countless corrupted packages transferred in ASCII mode.