If systemd was only managing services there would be less opposition. People opposed don't want a single thing doing services and boot and user login and network management and...
IDK, ask them. There are some in this thread. I'm addressing the strawman argument that people against it are luddites set in their ways over their beloved cron jobs.
If you use a debian-based system, unless you have actively looked at the DH source, the one thing that built virtually every package on your system, you do not get to say anything about "bloat" or "KISS".
DH is a monstrous pile of perl scripts, only partially documented, with a core design that revolves around a spaghetti of complex defaults, unique syntax, and enough surprising side effects and crazy heuristics to spook even the most grizzled greybeards. The number of times I've had to look at the DH perl source to understand a (badly/un)documented behavior while packaging something is not insignificant.
But when we replaced a bazillion bash scripts with a (admittedly opinionated but also stable and well documented) daemon suddenly the greybeards acted like Debian was going to collapse under the weight of its own complexity.
Oh yes, fuck dh with a rusty pole. I've had to paclage some stuff at work, and it's a nightmare. I love having to relearn everything on new compat levels. But the main problem is the lack of documentation and simple guidelines