Unfortunately they get poorly supported because everyone just assumes you have systemd.
No, they get poorly supported because they were a pain to support even before systemd ever showed up. I for one was extremely tired of writing the same shit over and over again in every init script and then going through the tedious process of porting the script to every platform for minor idiosyncrasies of the various distros (start-stop-daemon available or not was one I remember, the general bash/GNU vs. BSD stuff you get with any script was another) from 10 year old RHEL to modern ones.