Step 1, Notice bug
Step 2, Fix bug
Step 3, Deploy bugfix
The steps between 1 and 2 could obviously take a variable amount of time, but Step 3 is 'near instantaneous' on the web. The thought of having to relinquish deployment to somebody else, and that somebody else possibly taking a week to just alert users that there IS a bug fix, much less the time it takes for those users to see and apply the fix, that's a relative eternity.