The principle of “do one thing and do it well” still applies to SystemD as it builds into many different applications which each do one thing only. The problem is that you require most of them to have a fully functioning unit system which makes it function more like 1 big product rather than many smaller ones as it actually is.

A lot of the hate I feel started with Pottering which extended to SystemD. And while it certainly had downsides it had less than the other i it Systems which is also why It has become the new norm.