Moving fast and breaking stuff is OK if you're building a web service that doesn't really matter. If Facebook falls over, the productivity at a significant number of businesses probably goes up.
On the other hand, if yesterday's OS security patch stops everyone's PC from booting this morning, or if a new version of your e-mail server has a glitch that means half your company can't log in to read their mail or even that important messages from customers are actually being lost, that probably comes with a cost measured in large numbers of dollars per minute at a medium-sized business, or if you prefer, in careers per hour within the IT group.