Back when I recall the notion of "buy the 50% retracement", but I don't recall it being called the, "50% Fibonacci retracemtent". However, every Fib tool I've seen has the 50% retracement line included. What's your point? Is it that buying a 50% retracement is a bad play or is it that 50% is not a Fibonacci level and should NOT be referred to as such?
it is very important not to treat trading books like the bible. Most professional writers, no matter how famous they are, failed to spend thousands of hours staring at the charts. They and the publishers are very good at earning tons of money selling books.
Fibs fib alot but if you get enough on a chart you are bound to hit one correctly. However, a 50% retracement is a logical psychological level. Not a fib level.