I don't think it counts as a myth, mainly "misinformation" but a local wildlife center did a presentation at my high school (where I teach) and I got to sit in on it. She brought some native animals but also a BP. I had to stifle laughter when she told the class that BPs get up to 7-8' regularly. She was holding an adult, looked male, about 4' long lol. That was pretty bad IMO.