If those inits supported newer features, the init scripts would easily grow longer than a few lines and become incompatible once they use those features. I don'

If those inits supported newer features, the init scripts would easily grow longer than a few lines and become incompatible once they use those features. I don't see how that's any different from what's going on here. If your complaint is that the scope of init systems has been expanded, I don't know what to tell you other than that it was inevitable. Systemd is not the first project to try and do this.