When you are initiating, unless you are stomping, you don't simply just forget about your carries. I mean sure, you want to kill their carries asap, but that doesn't mean you don't try to protect your own carries unless you are so strong your carries can handle anti-carries by themselves.
While the act of initiation gives you the advantage of a first attack, it also distances yourself from your team, creating a gap in your lines that a well coordinated team can exploit. When you initiate, your (squishy) carries run forward to help you, right into range of all kinds of cc and gap closers. In a situation where you are stomping, this doesn't matter, because your carries can take care of themselves. If you are losing, what the heck are you doing initiating? But in a fairly even match up, it's highly like that their bruisers and tanks will jump onto your own carries, and bruisers who have managed to get close to and cc a carry are highly dangerous to a carry. If you blew your cc on the initiation, you need to back the fuck up and peel for your carries, because you sure as heck aren't going to catch the enemy carries without cc.
Pray to become a better man and for protection from things you cannot protect yourself from,
Fistful of Force.