Wow, if you call me an idiot, then I'll call you an ignoramus: Ignoramus!
This has nothing to do with systemd. systemd is just the messenger, telling you what has been the status quo since quite some time. Don't shoot the messenger!
systemd itself has no issues with running with a separate /usr. We have been very careful in distributing our stuff among / and /usr to make boots with separate /usr possible. But uh, systemd does not exist in a vacuum, and it won't magically fix all other software for you.
If anything at all you should congratulate us systemd developers for the fact that we spent so much time on detail work to actually make systemd itself work fine with separate /usr. And then we added the extra cherry on top in that we point you to the fact that in general this probably won't work well for you due to other programs.
And we did all this "separate-/usr-support" work for you even though we personally think splitting off /usr is a useless and pointless exercise.