My impression: For years it was common practice that when CAs messed something up it would cause some complains, but no real consequences. The large CAs thought

My impression: For years it was common practice that when CAs messed something up it would cause some complains, but no real consequences. The large CAs thought they were "too big to fail". They thought it would just go on like that. They (and many others in the industry) didn't believe that Google was serious when they threatened with browser removal. When they realized Google was serious it was too late to change their course.