Nobody else was paying for as many developers so all the other distros are repackaging RedHat's work.
I agree that RedHat investment helped to develop systemd and that RedHat can force systemd on RHEL and Fedora, leaving it's forks with little choice. But I don't believe that Debian, or Arch or openSUSE adopted it just because Red Hat did. If it was the case, rpm based package management would be on all Linux distributions.
There's still a design of binary logging, and not much of it, with a race condition that would earn a fail in a school project. There's been a stupid move to disable background tasks when a user logs off.
Let me guess, you have read countless discussions on slashdot and elsewhere about how binary logging is awful, then someone points out that plain-text logging is still there live and well. But the only thing you remember from the conversation is “binary logging”.
As for killing user background processes, it's a change of default option. You can change this default with compile flag or in /etc/systemd/logind.conf. In other words, it's up to the distributions to do what they feel is right (and for example, Fedora 25 does not kill by default), and if admin feels that distribution made the wrong choice, they can change one flag. I guess that after a month the only thing you will remember about background processes is that systemd kills them.
As for race conditions, I just don't know. Software as such is prone to such bugs, especially ones written in C, but given that your other examples of shortcomings of systemd where not that accurate, I'm not sure even this is not just some urban legend.