No, but they make many availability issues Someone Else's Problem.
When EC2 goes down, I need to maybe wake up and log in to see what happened. I see that all of us-east-1 is down (again), notify everyone involved: "It's down can't do anything, it'll come back up when AWS engineers get to it" and go back to bed.
I can check up on it again during office hours.
If this was a colocated server, I'd need to drag my ass out of bed and drive to the site to see what's up.