The Unix way, on the off-chance that it needs to be spelled out on HN, which I can hardly imagine, is to have independent tools that communicate in simple ways. The systemd way is opaque globs that are shipped as one large interconnected and interdependent system, where you no longer have much choice except to buy in to the whole thing all at once.
Unix has been able to adapt just fine and there is plenty of change over the years. But there has been very little 'change just to change', it usually was in order to tackle some concrete issue.
If all systemd did was to supply optional components that you can choose to run on top of or instead of the older versions then I'd be fine with that. It's this whole game of landgrab and forced incompatibility that gets me, besides the low quality of what is produced.
It is easy to point to 'deficiencies' and then use those for the next round of systemd landgrab, but I don't recall anybody actually complaining about this stuff to begin with.