It is true that blood cholesterol has nothing to do with arterial disease or heart disease but you can still find physicians checking peoples' cholesterol. I take my Lipitor not for trigycerides but because it seems to prevent heart attacks by some other kind of magic.
Medical and non-medical erroneous or pseudoscientific enthusiasms can last a generation because they infect the culture. Red meat and salt-avoidance, for examples. The 8 Stages of Scam
I recently saw a relative get into big trouble by believing the old "salt is bad" admonition. Skepticism is the best default setting in life.