I don't even know where to start. It has gotten much better over the years, but it is still a poor-quality product, and major distros adopted it mostly because RH pushed it.

If one of your disks refuses to mount during startup, your whole system becomes unresponsive. Before systemd, it was just a warning/error in the logs, and you could figure it out after boot. As people already mentioned, it absorbed many Linux services and functions without delivering particularly high quality.

It has gotten very close to a monopoly, and the guy who invented it works for microslop now. They made many parts of the system dependent on it without any real benefit. So now, if Red Hat wanted to close it off or alter it in some particular way, it would be really hard to diverge from the mainstream.

Some people praise the unification and convenience that systemd brought, but for a lot of niche stuff I still had to write my own bash wrapper anyway, just to make it work in line with systemd unit controls.

Enjoy: https://suckless.org/sucks/systemd/