Who needs an init system anyway

init=/bin/sh

Put everything you need to run automatically at startup in /etc/profile or one of the other autoexec files, and you won't have to deal with a mess of init scripts or the horrors of systemd. It's like AUTOEXEC.BAT for *nix, easy and simple. If you want a GUI just put startx in there...

So what's the deal with systemd?
Why's it so controversial and obviously hated yet at the same time popular among distributions?