There's a lot of BS lore in traditional cooking, such as "don't wash mushrooms, it makes them soggy (they don't absorb the water) and washes away the flavor (if you value dirt's and bugs' flavors).
"To keep it tender, float a cork in the water you're cooking octopus in" is one of my favorites. "Leave the seed in the avocado to keep it fresh" is one that still gets people angry when you attempt to disagree.
Bottom line: cooks aren't scientists; they're traditional crafts practitioners... at least until the advent of Alton Brown and company.
Sadly, this led to the fad of molecular gastronomy, but we may be coming out of that dark period of overindulgence.