Yes, a few times. One example: A friend had to submit an online form but made a mistake. The page allowed you to resubmit the data, except for some fields which became uneditable. As (bad) luck would have it, the error was in one of those. The fix would have involved calling the next day and dealing with DMV-like bureaucracy.

So I fired the browser developer tools and saw how the elements were disabled, made the correction, and resubmitted.