[datasink]

Having been in a high pressure position in which my team and I were writing mission critical code which could "have no bugs whatsoever" first without QA, and then later with QA, I can say confidently the quality of the code and occurrence of bugs dropped dramatically after we introduced our QA engineers.

Our prior condition was very similar to telling a newspaper writer "DONT WRITE TYPOS". You can scan a page you've written several times carefully and still miss your mistakes, even if you are a conscientious writer. And the newspaper industry isn't the only industry that prevents mistakes through multi-party review processes, either.