All OS have a multi phase booting cycle.
This only reduces the speed of the init phase of the booting cycle.
But typically, in a lot of modern linux distros system booting is very quick. It takes longer to get from login screen to desktop in many cases than it does to get from power=off to login screen.
But GUI initialization is being sped up too. See:
http://blog.martin-graesslin.com/blog/2012/04/improving-kwin-startup-performance/
It takes ma a while to get out of my comfort zone. I rebelled when GRUB came along since I was so accustomed to LILO. Now I look back and wonder what I was thinking by clinging to the familiar for so long.
I'm undergoing the same transition now as I get used to the new approach since the SysV init scripts were what I had been use to for so very long. Progress is disruptive and, for me, sometimes painful. But I can already see the benefits of the new way of launching services. It's not only faster but less brittle than the serialized order of the startup symlinks.
Very interesting - thanks for this. Just proves once again what a force Linux in general (and I claim Fedora/Red Hat in particular) is to keep pushing the envelope in all areas. I think any one innovation is not necessarily a game changer but all the innovations taken together do end up changing the game!