No, libsystemd did this because it’s a library. They went with pthread_at_fork as an alternative to detect when the application code forked, but it’s not without its own set of risks. Of course they could have required the user of the API supply the PID everywhere to avoid this but it’s possible even that wouldn’t solve the problem and it complicates the UI and the UI of the library API is equally important as other technical details - it’s a design tradeoff and judging it as some kind of correctness thing without having a clear picture and insulting the authors out of hand is weird behavior.

I agree with everything you said except that "systemd" and "insulting" don't go together like peanut butter and jelly. Insults seem to be the fuel the project is run on.