People spend a couple of years getting used to a stack in their early carrier and then spend decades arguing that it should never change.
A lot of that "python2 will never die" crowd left python all together, and they are better off for it because they won't have to deal with the next time python decides to throw everyone's work out the window.
Even when we can show am improvement in security and usability, and lower training cost because of consistency, it's still another mouth to feed.
Why are you talking in the past tense? We have done no such thing. Death to python 3; long live python.
But you are right, adoption is not enthusiastic, which to me is a massive indictment of the design and usability. We'll basically spin wheels until someone gets annoyed with it and does systemd better, or at least more modularized.
My complaint? sudo systemctl <verb> <service> means the verb cannot be autocompleted or introspected like sudo service <service> <verb> could be. May be minor, but it's generally my only interaction with systemd versus init.d, and to me they completely blew the only thing I use. Not a good impression.
I understand that init.d was a cobbled set of scripts, loose conventions, and even some hacks. But the resistance to system.d is so pervasive it cannot just be stubborn unix neckbeards.
Why else do you think so many distributions switched?
Yes, the resistance is noisy and stubborn Unix neckbeards. Not even Unix, since every other Unix had something similar to systemd already. LINUX neckbeards.