Name one commercial version of Unix that still is supported that uses init?
Sco Unixware is the only thing that comes close but I do not think it is supported anymore.
Solaris left init in 2008
Apple left init in 2006
NetBSD left init for object oriented macros in init for a hybrid approach around 2007
If Init is so great why is everyone leaving?
The reason is init was not designed for desktops or servers with more than a dozen applications. What if your laptop goes to sleep and wakes up on a different network? How can init with 200 lines of if/fi scripts handle something liek this? WHat if your network goes down on your server? What if your web server is hacked? What if your Oracle RDMS takes a dive?
Writting every possible conceivable combination of events with nested if/fi statements is luducrious! An event driven system makes sense.
FYI Init is not a glorified autoexec.bat for starting up. Something needs to tell the kernel which daemons to start and which arguments to pass on. Those who say otherwise do not know what Init does or it's intended use.
So Apple went 1st and everyone but Linux followed.