Bill Burr, the person responsible for advising us all to use a password that mixed letters and case with numbers and symbols (LikEtHi$1) was wrong.

So says Bill Burr himself:

http://www.cbsnews.com/news/bill-burr-passwords-guidance/

https://www.sciencealert.com/the-guy-who-wrote-the-book-on-passwords-now-wants-to-chuck-it-out